Updated Mineral Resource Report for the RHA Tungsten Project, › component › rsfiles... · 2 2....
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Updated Mineral Resource Report for the RHA Tungsten Project, 27 November 2016 Premier African Minerals The Croft, 87 Main Road, Bluehills(R55), 1685 +27 (0)10 020 0876 Gerard Evans & Bruce Cumming
Transcript of Updated Mineral Resource Report for the RHA Tungsten Project, › component › rsfiles... · 2 2....
Updated Mineral Resource Report for the RHA Tungsten Project, 27 November 2016
P r e m i e r A f r i c a n M i n e r a l s
T h e C r o f t , 8 7 M a i n R o a d ,
B l u e h i l l s ( R 5 5 ) , 1 6 8 5
+ 2 7 ( 0 ) 1 0 0 2 0 0 8 7 6
Gerard Evans & Bruce Cumming
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1. Project Sign-Off
This report was compiled and signed-off by the following key technical and
competent persons:
1. Geostatistical Work
__________________
Gerard Evans
Consulting Geologist (Premier African Minerals)
BSc. Hons Geology, Pr. Sci. Nat., GSSA, GASA
2. Qualified Person
__________________
Bruce Cumming
Competent Person (Premier African Minerals)
BSc. Hons Geology, Pr. Sci. Nat., GSSA
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2. Certificate of Competent
Person(s)
Gerard Evans is responsible for the compilation of all sections of this report. By
means of data review and discussion with the Competent Person, he is familiar
with the RHA Tungsten Project. He has used the information acquired to
generate the updated geological and resource models and to compile this report.
Gerard has been in the employ of Premier African Minerals Ltd since May 2016,
and the work undertaken to develop the resource model in this report has been
a combination of his own geological work and observations made on previous
operational level plans. He has read the SAMREC code, and has endeavoured to
prepare this report in compliance with that code.
Bruce Cumming is the Competent Person (CP) for the RHA project and the PREM
representative who worked on-site for the past few years, with a total of 40 years of
industry experience in the mining industry. Bruce has the required amount
experience to be classified as the CP in terms of the SAMREC requirements.
Bruce is a shareholder in Premier African Minerals Ltd (PREM).
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Table of Contents ........................................................................................................................................................ 0
1. Project Sign-Off ............................................................................................................................... 1
2. Certificate of Competent Person(s) ................................................................................................ 2
3. Executive Summary ......................................................................................................................... 8
4. Abbreviations/Acronyms/Definitions ........................................................................................... 10
5. Introduction .................................................................................................................................. 12
5.1 Scope of Work ........................................................................................................................... 12
6. Property Location and Description ............................................................................................... 14
7. Geological Setting ......................................................................................................................... 16
7.1 Regional tectonic setting .......................................................................................................... 16
7.2 Local Geology ............................................................................................................................ 17
7.3 Structural Geology .................................................................................................................... 18
8 Exploration and Drilling Review .................................................................................................... 20
8.1 Historical Exploration ................................................................................................................ 20
8.2 Data Collection .......................................................................................................................... 21
8.2.1 Underground ......................................................................................................................... 21
8.2.2 Boreholes and Surface Sampling .......................................................................................... 22
8.2.3 Cleaning, packing, marking and presentation....................................................................... 23
8.2.4 Sampling ................................................................................................................................ 24
8.2.5 Surveys and Collar Positions ................................................................................................. 26
8.2.6 Downhole Surveys................................................................................................................. 26
8.2.7 Database ............................................................................................................................... 27
8.2.8 Bulk Density .......................................................................................................................... 28
8.2.9 Data Confidence .................................................................................................................... 28
8.2.9.1 Drill Hole Database ............................................................................................................... 28
8.2.9.2 Underground Database ......................................................................................................... 29
8.2.10 Quality Assurance/Quality Control (QA/AQC) ...................................................................... 30
8.2.10.1 Laboratory ......................................................................................................................... 30
8.2.10.2 Certified Reference Materials ........................................................................................... 30
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8.2.10.3 Sampling Routine .............................................................................................................. 31
8.2.10.4 Precision ............................................................................................................................ 31
9. Geological Modelling ........................................................................................................................ 32
9.1 Underground Mapping ............................................................................................................. 32
9.1.1 Inter-Lode Mineralisation ..................................................................................................... 34
9.2 Geological Nomenclature ......................................................................................................... 36
9.3 Geological Structures ................................................................................................................ 37
9.4 Open Pit Mapping ..................................................................................................................... 37
9.4.1 Mineralised Wireframe for the Open Pit .............................................................................. 39
10 Geostatistical Analysis ............................................................................................................... 41
10.1 Underground Geostatistical Analysis ........................................................................................ 41
10.1.1 Lode 2 .................................................................................................................................... 41
10.1.2 Lode 4 .................................................................................................................................... 42
10.1.3 Lode 5 .................................................................................................................................... 43
10.1.4 Lode 7 .................................................................................................................................... 44
10.1.5 Splay Lode ............................................................................................................................. 45
10.1.6 Geostatistical Analysis ........................................................................................................... 45
10.1.6.1 Basic or Raw Geostatistical Analysis ................................................................................. 45
10.1.6.2 Composite Data Geostatistical Analysis ............................................................................ 48
10.1.6.3 Grade Indications from Falconbridge Data ............................................................................. 49
10.2 Inter-lode Geostatistical Analysis.............................................................................................. 51
10.3 Open Pit Geostatistical Analysis ................................................................................................ 51
10.4 Variography Analysis ................................................................................................................. 53
10.4.1 Underground Lodes Variograms ........................................................................................... 53
10.4.1.1 Lode 4 Variogram .............................................................................................................. 53
10.5 Open-Pit Variography ............................................................................................................... 55
10.6 Search Parameter Files ............................................................................................................. 57
10.7 Estimation Parameter Files ....................................................................................................... 59
11 Resource Block Model............................................................................................................... 60
11.1 Model Origin ............................................................................................................................. 60
11.2 Block Models ............................................................................................................................. 60
11.3 Model Validation ....................................................................................................................... 61
12 Mineral Resource Statement .................................................................................................... 63
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12.1 Underground Resources ........................................................................................................... 63
12.1.1 Lode 2 .................................................................................................................................... 63
12.1.2 Lode 4 .................................................................................................................................... 64
12.1.3 Lode 5 .................................................................................................................................... 66
12.1.4 Lode 7 .................................................................................................................................... 67
12.1.5 Splay Lode ............................................................................................................................. 68
12.1.6 Inter-lode 4A ......................................................................................................................... 69
12.1.7 Inter-lodes 4B & 4C ............................................................................................................... 69
12.1.8 Inter-lode Lode 2 HW1 .......................................................................................................... 69
12.1.9 Inter-lode Lode 2 HW2 .......................................................................................................... 70
12.1.10 Inter-lode Lode 2 HW3 ...................................................................................................... 70
12.1.11 Inter-lode Lode 2 HW4 ...................................................................................................... 70
12.2 Open Pit Resources ................................................................................................................... 71
12.3 Open Pit Inventory .................................................................................................................... 72
12.4 Resource Statement Summary ................................................................................................. 73
13 Conclusion ................................................................................................................................. 75
14 CERTIFICATE OF DISCLOSURE .................................................................................................... 76
15 Appendix 1 ................................................................................................................................ 78
16 Appendix 2 ................................................................................................................................ 82
17 Appendix 3 ................................................................................................................................ 85
18 Appendix 4 ................................................................................................................................ 90
List of Tables
Table 1: Underground Sampling Summary ........................................................................................... 21
Table 2: Drill Hole Summary ................................................................................................................. 22
Table 3: Trenching Summary ................................................................................................................ 23
Table 4: Drill hole intersects into Lode 2 .............................................................................................. 42
Table 5: Drill hole intercepts into Lode 4 .............................................................................................. 42
Table 6: Drill hole intercepts into Lode 5 .............................................................................................. 43
Table 7: Drill hole intercepts into Lode 7 .............................................................................................. 45
Table 8: Basic Statistics of the Lodes .................................................................................................... 46
Table 9: Statistics of composited data .................................................................................................. 49
Table 10: Statistics of available Falconbridge data ............................................................................... 50
Table 11: Basic statistics of the inter-lodes .......................................................................................... 51
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Table 12: Raw statistics of the open-pit data ....................................................................................... 51
Table 13: Summary of Lode 4 variography ........................................................................................... 54
Table 14: Summary of underground lodes search parameters ............................................................ 58
Table 15: Summary of open pit search parameters.............................................................................. 58
Table 16: Estimation Parameter file descriptions ................................................................................. 59
Table 17: Block Model Origin ................................................................................................................ 60
Table 18: Correlation Coefficients ........................................................................................................ 62
Table 19: Grade and Tonnages for Lode 5 ............................................................................................ 66
Table 20: Grade and Tonnage of Inter-Lode 4A .................................................................................... 69
Table 21: Grade and Tonnage of Inter-Lodes 4B & 4C .......................................................................... 69
Table 22: Grade and Tonnage of Inter-lode 2 HW1 .............................................................................. 69
Table 23: Grade and Tonnage for Inter-Lode 2 HW2 ............................................................................ 70
Table 24: Grade and Tonnage for Inter-Lode 2 HW3 ............................................................................ 70
Table 25: Grade and Tonnage for Inter-Lode 2 HW4 ............................................................................ 70
Table 26: Summary of RHA Grades and Tonnages ............................................................................... 74
List of Figures
Figure 1: Location of RHA in Zimbabwe ................................................................................................ 14
Figure 2: PREM Interests in Zimbabwe ................................................................................................. 15
Figure 3: RHA Geological Setting .......................................................................................................... 16
Figure 4: Typical Cross Section in the 1940s ......................................................................................... 18
Figure 5: Major Underground Lodes ..................................................................................................... 19
Figure 6: Core Logging at RHA ............................................................................................................... 24
Figure 7: Underground mapping of Lode 4 - 870 Level ........................................................................ 33
Figure 8: Location of Inter-lodes 4A, 4B and 4C ................................................................................... 34
Figure 9: Location of lodes and Inter-lodes east of Lode 2 ................................................................... 35
Figure 10: Underground Nomenclature for the Lodes ......................................................................... 36
Figure 11: Location of the fault plane in the pit ................................................................................... 38
Figure 12: Shape of the mineralisation on the open-pit ....................................................................... 40
Figure 13: Falconbridge sampling of Lode 5 ......................................................................................... 44
Figure 14: Histograms for the respective lodes .................................................................................... 48
Figure 15: Cumulative histogram of sample lengths ............................................................................ 49
Figure 16: Example of Falconbridge sample data ................................................................................. 50
Figure 17: Histograms of the open-pit data .......................................................................................... 52
Figure 18: Variography of Lode 4 .......................................................................................................... 54
Figure 19: Variography of open pit data above 0.5kg/t cut-off ............................................................ 56
Figure 20: Variography of open pit data below 0.5kg/t cut-off ............................................................ 57
Figure 21: Lode 4 Grade Model ............................................................................................................ 60
Figure 22: Lode 4 Resource Classification ............................................................................................. 61
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Figure 23: Lode 2 Indicated Resource ................................................................................................... 63
Figure 24: Lode 2 Inferred resource...................................................................................................... 64
Figure 25: Lode 4 Measured Resource ................................................................................................. 65
Figure 26: Lode 4 Indicated Resource ................................................................................................... 65
Figure 27: Lode 4 Inferred Resource ..................................................................................................... 66
Figure 28: Lode 7 Indicated Resource ................................................................................................... 67
Figure 29: Lode 7 Inferred Resource ..................................................................................................... 67
Figure 30: Splay Lode Indicated Resource ............................................................................................ 68
Figure 31: Splay Lode Inferred Resource .............................................................................................. 68
Figure 32: Open Pit Grade-Tonnage Graph (Total) ............................................................................... 71
Figure 33: Open Pit Indicated Resource................................................................................................ 71
Figure 34: Open Pit Inferred Resource ................................................................................................. 72
Figure 35: Inventory of mineralisation below the open pit to 735 A.M.S.L. ........................................ 73
Figure 36: Appendix 1 – Underground Swath Plots .............................................................................. 80
Figure 37: Appendix 1 - Open Pit Swath Plot ........................................................................................ 81
Figure 38: Appendix 2 - QQ Plots .......................................................................................................... 85
Figure 39: Appendix 3 - Lode 2 Longitudinal Sections .......................................................................... 86
Figure 40: Appendix 3 - Lode 4 Longitudinal Sections .......................................................................... 87
Figure 41: Appendix 3 - Lode 7 Longitudinal Sections .......................................................................... 88
Figure 42: Appendix 3 - Splay Lode Longitudinal Sections .................................................................... 89
Figure 43: Appendix 3 - QA/QC CRM Certificates and Analysis ............................................................ 93
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3. Executive Summary
The RHA Tungsten Mine located in the Hwange area of Zimbabwe is one of the
operations owned by Premier African Minerals (PREM). Since the acquisition of
the property, various resource statements have been produced: Du Plessis &
Ingram in 2012, Chisonga and Crossingham in 2013 and Chisonga and Cumming
in 2014.
For these reports, the then named Lode 1 (Lode 1E, Lode 1W, Lode 1FE and
Lode 2HW) and Lode 2 (Lode 2E, Lode 2W, Lode 2HE and Lode 2HW) were
reported. This report will cover Lodes 2,4,5,7 and inter-lodes 4a, 4b, 4c, 2HW1,
2HW2, 2HW3 and 2HW4 that make up the underground operation and the
multiple lodes that occur in the open cast operation. The naming convention
here is adopted from the old mining operations, but not the inter-lodes.
Most of the Lodes are generally trending in an east - west orientation with a
steep dip anywhere between 65-75o (N). The exception to this is the Lodes 2 & 4
in the underground operation that have a more north west – south east
orientation but still have a dip also of 65-75o (NE). From pervious drilling
campaigns, it is found that ore bands have been intersected at depth.
Resource models have been generated for the lodes mentioned above. It is only
on Lode 4 that there is a small amount of measured resource, while all the other
lodes are either indicated or inferred resources. This is based on the proximity of
the sample data and an understanding of the ore body. The assumption is made
that above 926 level, everything has been mined out. Then for Lode 2, this lode
was extensively mined from the 865 level. All resources reported for Lode 2 are
below 865 level.
Fieldwork is now indicating that there is no continuity from the underground
lodes into the open pit area. All mineralisation in the pit will be considered
independent from the underground lodes. Due to the lensoidal nature of the
mineralisation, a predictive model was used for the generation of the resource
block model in the pit.
The quality of the sample data that is at PREM’s disposal can be deemed as
reliable with the required QA/QC reports. All assay analysis is conducted at site
where a Dual Beam Analyser is used. With this data, the geological models were
constructed for the resource model estimation. With time, with more sample
data the confidence of the mineral resource will continually improve.
In instances where there is not enough sampling data available, the Falconbridge
data (previous owners) was considered for comparison purposes. There is no
QA/QC available for this data for it to be considered as trustworthy.
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The tonnages and grade for the respective Lodes are tabulated below.
Lode Resource Category
Below Level
Tonnes Metal
Content (kg)
WO3 Grade (kg/t)
2 Indicated 865 2,081 2,767 1.33
2 Inferred 865 97,964 264,504 2.70
4 Measured 926 21,912 78,665 3.59
4 Indicated 926 38,961 169,478 4.35
4 Total 60,873 248 0.00
4 Inferred 926 180,107 828,491 4.60
5 Inferred 926 166,883 417,208 2.5
7 Indicated 926 16,168 13,151 0.81
7 Inferred 926 155,508 113,003 0.73
Splay Inferred 926 41,602 265,005 6.37
4A Inferred 926 106,114 397,966 3.75
4B Inferred 926 15,351 68,025 4.43
4C Inferred 926 17,464 118,607 6.79
2 HW1 Inferred 926 243,434 1,562,235 6.42
2 HW2 Inferred 926 29,308 34,877 1.19
2 HW3 Inferred 926 108,871 947,315 8.70
2 HW4 Inferred 926 25,427 109,845 4.32
Open Pit Indicated 707,248 1,039,655 1.47
Open Pit Inferred 2,460,120 3,714,781 1.51
Total Measured Indicated
U/G 79122 264,061 3.34
Open Pit 707248 1,039,655 1.47
Total Inferred
U/G 1188033 5,127,079 4.32
Open Pit 2460120 3,714,781 1.51
The Falconbridge data does however suggest that that the Lode 2 Inferred
resource could be 5.60kg/t and the Lode 7 Inferred resource 2.74kg/t.
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4. Abbreviations/Acronyms/Definitions
Term Definition Qualified Person i. An Engineer or Geoscientist with at least five (5) year’s experience
in mineral exploration, mine development or operation or mineral project assessment, or any combination of these.
ii. Has experience relevant to the subject matter of the mineral project and the technical report, and
iii. Is in good standing with a professional association
COV Geostatistical term: Coefficient of Variation. The is derived by dividing the Standard Deviation of a data set by the mean of the data set.
Dip Geological term: the angle that a geological structural surface or bedding plane or fault plane measured perpendicular to the strike of the structure.
Drillhole A hole drilled from surface or underground in which the core of the rock strata is cut by a diamond tipped bit or crown. The core is retrieved and studied, split by a diamond cutter where one half is sent off for analysis. This determines the amount of contained mineral (metals) within. This is referred to as assaying.
Exploration This involves either prospecting, sampling, mapping, diamond drilling and other similar work to search for mineralisation.
Fault Geological term: a fracture in earth materials along which the opposite sides have been displaced from one another.
Faulting The process of fracturing that produces a displacement.
Grade The quality of metal per unit mass of ore expressed as a percentage or as grams per tonne of ore.
Inferred Mineral Resource
The part of a mineral resource for which tonnage, grade and mineral content can be estimated with a low level of confidence. It is inferred from geological evidence and assumed but not verified geologically and/or grade continuity. It is based on information gathered through appropriate techniques from locations such as outcrops, trenches, pits, workings and drilling that may be limited or reliability. An Inferred Mineral Resource has a lower level of confidence than that of an Indicated Mineral Resource.
IPD Geostatistical term: Inverse Power of Distance. Can be used in mineral resource estimation
Kg/t Kilogram per tonne
Mean Average
Mineral Resource A concentration (or occurrence) of material of economic interest in or on the
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earth’s crust in such form, quality and quantity that there are reasonable and realistic prospects for eventual economic extraction. The location, quantity, grade, continuity and other geological characteristics of a mineral resource are known, estimated from specific geological evidence and knowledge, or interpreted from a well-constrained and portrayed geological model. Mineral resources are subdivided in order of increasing confidence in respect of geoscientific evidence into Inferred, Indicated and Measured categories (SAMREC definition).
Mineralised Area The presence of a target mineral in a mass of host rock.
Ore Body A continuous, well –defined mass of material of sufficient ore content to make extraction economically feasible.
ppm Parts per million
QA/QC Quality Assurance / Quality Control.
RD Relative Density (or Specific Gravity). This is a measure of the density of a material. It is dimensionless, equal to the density of the material divided by some reference density (most often the density of water but sometimes the air when comparing to gases).
Sampling Taking small representative pieces of rock at pre-determined intervals. This occurs at exposed places of mineralisation. These pieces are then sent for assaying.
SAMREC Code The South African code for the reporting of exploration results, mineral resources and mineral reserves.
Strike The direction of the line formed by the intersection of a fault, bed, or other planar feature and a horizontal plane. Strike indicates the attitude or position of linear structural features such as faults, beds, joints, and folds
Tonnage Quantities where the tonne is an appropriate unit of measure; typically used to measure reserves of gold-bearing material in situ or quantities of ore and waste material mined, transported or milled.
Trend The direction of the line formed by the intersection of the planar feature with the ground surface; trend is the same as strike only if the ground surface is parallel to the horizontal plane.
WO3
Tungsten tri-dioxide
Wolframite A tungsten laden mineral with the composition formula: (Fe,Mn)WO4
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5. Introduction
Premier African Minerals (PREM) is a London-listed mining company (LON:
PREM) with mining and exploration interests in Africa. Their flagship project is
the RHA Tungsten Mine, located approximately 270km northwest of Bulawayo or
130km south of Victoria Falls in Zimbabwe. The commodity mined is tungsten
(WO3 (tungsten trioxide) or (Fe, Mn) WO4 (wolframite)).
Since 2012, there have been a few mineral resource statements that have been
produced. The first was produced by Du Toit and Ingram in 2013, followed by
three reports by Datamine (Chisonga) in collaboration with RHA, in 2014 and
2015. Therefore a number of revisions to the Mineral Resource have been
reported in public and internal documents. The latest publicly available report
was the 5 September 2014 Updated Mineral Resource Statement - 2014
Technical Report, (Chisonga & Cumming).
Since the publication of these reports, further exploration has been undertaken,
both underground and open pit.
In May 2016, the author was engaged by Premier African Minerals (PREM) to
review the geological work undertaken as PREM was experiencing an unexpected
grade-gap, especially in the open pit operation. This report focuses on reporting
a combined Mineral Resource for the whole property by incorporating all
exploration and mining information available, underground and open pit
observations undertaken by the author with revised geological interpretation.
This culminated in a revised resource model that details the unmined
underground resource.
5.1 Scope of Work
The primary objectives of the technical report are the following:
Review and confirm the geological interpretations of the ore lodes
underground and in the open pit
Taking into consideration of any new geological interpretation(s), to
generate an updated geological and resource model.
Review the resource classifications and possible increase the confidence
limit of the resource.
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Report a Mineral Resource with Grade and Tonnes depleted to the current
mining
When PREM acquired the ownership of RHA, historical data was available.
However, there are no QA/QC verifications on this data and the assay
sample pulps are no longer available. Therefore any historical data used
was primarily for reference consideration only, and as such no historical
assay data was used in the generation of the resource model.
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6. Property Location and Description
This section is based on the description provided in the Chisonga and Cumming
(2014) Technical report, produced by Datamine Software.
The RHA Project is located in the Matabeleland North province of Zimbabwe,
about 20 km south-east of Hwange and 270 km north of Bulawayo, the
provincial capital (Figure 1). The whole country is well connected by a network of
roads and railways, with links to other countries.
Figure 1: Location of RHA in Zimbabwe
The project covers 1,800 ha land holding and is located close to other properties
owned by PREM in the north-western part of Zimbabwe (Figure 2). It is
accessible to Bulawayo by means of tar road, while the railway line running from
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Bulawayo to Hwange is within a 50 km radius. Du Plessis and Ingram (2013)
report that the project is comprised of 50 Mineral Claim Blocks, consisting of 10
owned by PREM and 40 blocks which are under option.
Figure 2: PREM Interests in Zimbabwe
The historic RHA Mine is on low ridge of approximately 850m long and 350m
wide standing about 80m above its surroundings. Evidence of historic mine
workings (trenches, pits, pegs shafts etc.) is visible on the ridge and surrounding
area (Du Plessis and Ingram, 2013).
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7. Geological Setting
7.1 Regional tectonic setting
The geology of Zimbabwe is dominated by Archean rocks which are overlain, in
the northwest, by Proterozoic and Phanerozoic metamorphic and sedimentary
rocks, in the area of the RHA Tungsten project (Figure 3.1). In this area,
phyllites, quartzites and gneisses are the dominant rocks.
Du Plessis and Ingram (2013) report that the host country-rock comprises high-
grade, strongly foliated biotite schists and paragneisses of the Precambrian Dete
Inlier belonging to the Tshontada Formation. The formation trends northeast on
a regional scale, paralleling the trend of the Kamativi Inlier, and dips steeply to
the northwest (Figure 3).
Figure 3: RHA Geological Setting
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7.2 Local Geology
Du Plessis and Ingram (2013) provide a concise geological description of the
RHA Tungsten project and surrounds.
In the project area, the tungsten-bearing rocks occur as sub-vertical parallel
lodes and veins that occur within an envelope that may be extensive over a
strike of approximately ~1 km.
The lodes have a northeast – southwest strike, parallel to the regional trend of
Kamativi Inlier. Tungsten mineralisation occurs in quartz veins and shear zones
in a sequence of quartz-tourmaline and pelitic (quartz-biotite-garnet) schists
that may be intruded by later granitic intrusions. The primary tungsten mineral
of economic interest is wolframite ((Fe,Mn)WO4).
Seven lodes were historically recognized at the RHA Tungsten Project, and were
captured and modelled as such by Datamine previously (Chisonga and
Crossingham, 2013). These lodes were numbered, in order from north to south,
as Lode 1 to Lode 7. These lodes are steeply dipping to the northwest at 65° to
75° (Figure 4). Recent mining and exploration activities, however, has shown
that there may be more than the historically numbered lodes, with several
tungsten-bearing structures observed in the north.
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Figure 4: Typical Cross Section in the 1940s
7.3 Structural Geology
Taken from the Chisonga and Cumming report, the following was stated. It is
believed that the lodes have developed along planes of weakness that opened up
above the apex of a granite intrusion. The tourmaline lodes later underwent
brittle deformation allowing the emplacement of quartz veins (Du Plessis and
Ingram, 2013). A later phase of deformation caused shattering of the tourmaline
schist and shearing of the quartz veins.
A number of structures were historically mapped, and at least three prominent
structures were postulated, although it is not known how these have impacted
the mineralization.
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From current structural mapping conducted on the 870 and 926 levels, only a
few structural faulting features have been observed and mapped. This has led to
a new understanding that the lodes observed underground are not the same to
those observed in the open pit. From a recent geological mapping exercise
undertaken, it is now believed that a fault has interrupted the continuity of the
lodes from underground to the open pit, (Figure 5)
However, there is a predominance of jointing that does occur that has a general
trend of north west – south east, dipping south west at roughly 40-50o.
Figure 5: Major Underground Lodes
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8 Exploration and Drilling Review
8.1 Historical Exploration
The RHA Mine, precursor to what is now known as the RHA Tungsten project,
was in production during the early part of the 20th century. The production
history is well summarized by Du Plessis and Ingram (2013). Based on available
data, is appears that for almost 100 years, the RHA mine has gone through
different owners, from the early 1900s when Bechuanaland Exploration Co. first
pegged the property to the late 1970s when Falconbridge (Blanket Mines)
undertook exploration and mining which consisted of detail underground channel
sampling of the developed areas from previous workers and further open pit
mining of the existing open pit. All work came to a premature end due to
security concerns and was never re-started in the post-1980 Independence era.
However, it was only in the late 2000, that the start of exploration using modern
exploration methods was applied to the project. In 2008, Arcadia Energy and
Mining listed a resource number of 250,000 tons of lode carrying 1.1% WO3
may be present below the 926 m level and above the 846 m level, of which
86,000 tons may carry 2.2% WO3.
Exploration activity on the project conducted by PREM commenced in January
2012 when they completed a 1,302.02 m diamond drilling, which consisted of
five holes (DD002 – DD006) inclined at -45 degrees. From this data initial
geological models for all the lodes, and a resource model for only Lode 2
(defined at that time), were generated Chisonga and Crossingham (2013).
Further drilling in 2013 by PREM resulted in 12 inclined diamond drill holes
totalling 1,300.7 m. Geological logging and sampling of the mineralised
intersections followed thereafter. This is complemented by 12 Percussion
drillingor RC drilling, (PH series), completed in 2015. With the onset of mining in
2014, underground channel sampling, pegs and bench composite data are now
available.
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8.2 Data Collection
Underground 8.2.1
The 2012 and 2013 drilling programme were both overseen by PREM. All the
trench and production sample and survey data has been added to the latest
database. PREM has the capability of undertaking on-site assay work which
assists in the turn-around time of getting assay results within a short period.
The machine utilised for this work is an Olympus Delta Dual Beam Analyser
which analyses powder disks via a fixed station setup. As per any QA/QC
requirement, standards, blanks and repeats are analysed too. The calibration
certificates are available and stored on site.
In the course of 2016, doubt arose over trustworthiness of the underground
samples. In May 2016, RHA took the initiative to conduct a new underground
sampling campaign to cover the areas of doubt. For this exercise, stringent
QA/QC procedures were followed. Channel samples lines were cut using a
diamond saw every 3m on the 870 Level (Lodes 4 & 5), Level 865 (Lode 2),
Level 875 (Lode 4) and Level 884 (Lode 4 and Splay Load). In total, 382 sample
lines were cut, sampled and assayed. This underground sample database now
replaces the previous underground database and is included in the resource
estimate in this report.
A summary of the latest underground sampling can be seen in the Table below,
(Table 1).
Table 1: Underground Sampling Summary
Level No of
Section lines
Total No. of Samples
Total length
Sampled (m)
865 53 152 63.93
870 247 463 200.90
875 16 37 14.28
884 66 160 54.80
Total 382 812 333.91
22
Boreholes and Surface Sampling 8.2.2
Numerous drilling campaigns and trenching campaigns have been undertaken in
the past, and this data was used for previous resource estimates. Since the
advent of this current resource estimate, no new drillhole has been drilled or
trench dug, (only the underground database has changed). Therefore the
methodologies described in the Chisonga – Cumming report is still valid.
A table describing the drilling and trenching campaign are shown below, (Table 2
& 3)
Table 2: Drill Hole Summary
BHID EASTING NORTHING ELEVATION AZI_TN DIP EOH YEAR
RHADD02 460922.637 7953563.463 927.186 152 -45 250.50 2012
RHADD03 460999.353 7953640.168 929.554 157 -45 300.00 2012
RHADD04 461107.979 7953689.501 927.170 172 -45 250.94 2012
RHADD05 461233.337 7953772.359 929.451 192 -45 250.50 2012
RHADD06 461384.072 7953760.632 923.510 182 -45 250.08 2012
RHADD07 460922.335 7953564.130 927.277 152 -70 124.70 2013
RHADD08 460999.065 7953640.754 929.566 157 -65 140.00 2013
RHADD09 461107.914 7953690.136 926.951 172 -60 170.00 2013
RHADD10 461043.487 7953668.372 927.772 157 -45 130.00 2013
RHADD11 461043.294 7953668.935 927.661 157 -60 160.00 2013
RHADD12 460955.630 7953613.474 928.063 152 -45 100.00 2013
RHADD13 460955.304 7953614.292 927.940 152 -65 136.50 2013
RHADD14 460881.799 7953537.671 928.045 152 -45 60.00 2013
RHADD15 460881.410 7953538.391 927.944 152 -65 115.00 2013
RHADD16 461065.845 7953611.009 948.916 157 -45 45.00 2013
RHADD17 461114.121 7953649.265 944.718 172 -45 60.00 2013
PH1 460843.636 7953474.713 932.666 132.03 43.07 21 2015
PH2 460848.083 7953483.650 932.209 141.42 46.88 20.5 2015
PH3 460855.665 7953490.369 932.092 139.97 49.15 22.5 2015
PH5 460871.580 7953502.163 932.565 122.95 38.63 21 2015
PH6 460878.308 7953510.890 932.220 128.37 42.48 21 2015
PH7 460884.995 7953517.662 932.022 134.13 45.15 20 2015
PH8 460892.493 7953523.658 932.100 154.20 36.58 20 2015
PH9 460901.481 7953528.371 932.737 141.52 53.35 20.5 2015
PH10 460851.265 7953468.116 932.926 135.60 57.53 21 2015
PH11 460858.338 7953475.109 932.416 137.30 46.95 21 2015
PH12 460864.381 7953483.042 932.522 129.62 41.20 20.5 2015
PH13 460879.453 7953494.924 933.227 126.33 40.58 21 2015
23
Table 3: Trenching Summary
BHID EASTING NORTHING ELEVATION AZI_TN DIP EOH YEAR
TR02a 460922.637 7953563.463 927.186 147 8 15.10 2013
TR03 460999.353 7953640.168 929.554 153.000 15 80.00 2013
TR04 461107.979 7953689.501 927.170 171.000 26 105.00 2013
TR05 461233.337 7953772.359 929.451 188.000 5 160.00 2013
TR06 461384.072 7953760.632 923.510 174.000 8 115.000 2013
TR0 460816.27 7953370.64 936.71 59 5 66.60 2015
TR01 460780.95 7953444.09 919.98 145 7 14.90 2015
TR02 460806.08 7953473.01 926.98 136 8 88.80 2015
TR02_Ext 460877.00 7953400.00 943.00 147 8 46.40 2015
TR07 460824.87 7953488.15 927.70 137 19 141.00 2015
TR08 460945.00 7953528.00 942.33 147 10 31.70 2015
TR09 460841.00 7953502.00 927.10 138 10 121.70 2015
TR10 460861.00 7953520.00 924.00 138 19 77.30 2015
TR11 461244.00 7953443.00 941.77 157 25 35.20 2015
TR12 461263.00 7953452.00 942.95 158 20 27.20 2015
TR13 461299.00 7953464.00 943.43 166 15 14.90 2015
TR14 460810.00 7953438.00 931.78 48 6 34.00 2015
The log sheets for both phases of drilling are complemented by pictures of core,
which are available. Also, half sections of core, and in some cases complete
sections of core, are available for visual validation. This has been inspected by
the author a site visit to RHA. The Competent Person for this report has visually
inspected the core against the logging sheets and deemed as true / accurate.
The logs are detailed recordings of information on lithology, vein, thickness etc.
Detailed geological information has been added as updates to the logs at some
time during and after their original generation. Core recoveries and RQD values
are generally good, especially in mineralised areas were 100% recovery was
achieved. The Core recovery values are stored in the RHA Drill Database.
Cleaning, packing, marking and 8.2.3
presentation
Drilling and core handling was supervised by PREM personnel. The core is packed
into metal core trays onsite with plastic core block markers after each core run,
inserted into the core tray and marked with the drill hole depth using indelible
24
marker pens. The core trays were later transported to a secure facility at
Bulawayo rented by PREM.
Figure 6: Core Logging at RHA
Sampling 8.2.4
The procedures below are described from previous reports by Du Plessis &
Ingram and Chisonga & Cumming. As there has been no subsequent drilling, this
methodology described below is still valid.
2012 programme: These procedures were supervised by PREM personnel.
The core was cut by diamond saw, first into halves and then one half was
cut into quarters.
The quarter core was sampled from core block marker to core block
marker, i.e. approximately representative of 3 m lengths.
Samples were assigned unique sample numbers from printed ticket books.
25
The core was placed in clear plastic bags and stapled closed with one
ticket in the bag and the other ticket stapled on the outside. The ticket
stub remains in the ticket book.
Samples were then placed in thick woven plastic bags which were marked
up and tied closed.
Samples were inspected by the Zimbabwean Government Engineer and
certified for export.
The samples were transported in a number of individual batches to SGS
Lakefield (SGS) in Johannesburg by a road-use courier. As no on-site
laboratory is present at this stage, the project is still in the exploration
phase, thus the samples were sent to SGS, which is a well-recognized
laboratory with the relevant ISO and SANAS certification.
At SGS, the core samples were weighed, crushed and milled following
their standard procedures.
All samples were assayed for tungsten (WO3) and copper (Cu) using a
variety of different XRF methods to establish best technique.
From these tungsten assays, a second more detailed core sampling
programme was conducted. Areas of core with elevated tungsten were
then logged and sampled in detail.
Coarse and fine grained quartz blank samples obtained from AMIS in
Johannesburg were alternatively inserted every 10th sample while every
10th sample was accompanied by one of two certified reference material
(CRM) obtained from Geostats in Australia – see Appendix 11.1.4 for their
certificates.
During this round of sampling, half cores were submitted for assay.
Sample marking and bagging followed the procedures as detailed above.
These samples were sent to SGS for sample preparation followed by
tungsten (W%) and copper (Cu%) assays using standard lithium borate
fused disc XRF.
2013 programme: The drill procedures were as follows. All core-handling and
sampling was done under the supervision of PREM personnel.
After zones of wolframite mineralisation were identified and logged, the
core was cut in half with a core saw.
Half core samples were assigned unique sample numbers from printed
ticket books.
The half cores were placed in clear plastic bags and stapled closed with
one ticket in the bag and the other ticket stapled on the outside. The
ticket stub remains in the ticket book.
Samples were then placed in thick woven plastic bags which were marked
up and tied closed.
Samples were inspected by the Zimbabwean Government Engineer and
certified for export.
26
Sample numbers were allocated for the QAQC reference materials. These
reference materials were inserted into the sample stream at SGS after
inspection by PREM personnel.
Fine grained quartz blank samples obtained from AMIS in Johannesburg
were alternatively inserted every 20th sample while rounded pebbles from
a garden nursery were purchased and used as coarse blanks and inserted
every 20th sample. Every 10th sample was accompanied by one of two
certified reference material (CRM) obtained from Geostats in Australia –
see Appendix 11.1.4 for their certificates.
The samples were transported in one batch to SGS Lakefield (SGS) in
Johannesburg by airfreight. (As no on-site laboratory is present at this
stage, the project is still in the exploration phase, thus the samples were
sent to SGS).
At SGS, the core samples were weighed, crushed and milled following
their standard procedures.
All samples were assayed for tungsten (WO3%) and copper (Cu%) by
lithium borate fused disc XRF.
Surveys and Collar Positions 8.2.5
There have been various times in the history of RHA that mining activity has
occurred. Also over this time various survey grids have been utilised too.
In order to ensure that a set grid system be implemented at RHA, Mr. P
Drysdale, L.S (Botswana), Pr.L.S. (SA) (PLS1228), of Drysdale and Associates,
Francistown, Botswana conducted 2 detailed surveys at RHA. The survey was
based on the UTM 35S ARC 1950 (Clarke 1880) system, with control points sited
at existing beacons.
All collar position and trench localities were surveyed as was a number of data
points that were used to create a DTM of the immediate area.
Trench survey data which was not available in the in the 2012 drilling campaign,
but is now incorporated as it is now accurately surveyed. No transposition errors
were found .
Downhole Surveys 8.2.6
Downhole surveys were not carried out in the 2012 drilling campaign, but were
conducted in the 2013 campaign. The 2012 drilling contractor at that time
assumed that the holes had the same inclination as planned. As such, any
27
resource classification using these holes can only be classified as inferred
resource.
In the 2013 campaign, downhole dip and azimuth measurements were taken
every 30 m downhole. A Flex-It downhole tool was used for this purpose.
Database 8.2.7
The RHA Tungsten Project database is hosted in two Microsoft Excel databases
for the project information. The first is a database which has all the diamond
drill, percussion and trench sampling conducted at RHA. The second database is
has all the underground sampling data that has been gathered since May 2016.
Every time the database is updated, it is time stamped accordingly and the old
database moved to the PREM central server. This then allows PREM personnel to
always have a reference database at certain time periods. For the time being,
this applies primarily to the underground database.
For the purpose of resource modelling, these two databases are joined, but for
practical day-to-day purposes, they will remain separate. It is acknowledged that
using MS Excel spreadsheets is not ideal and that a robust industry accepted
database management system should be considered for the future. However,
once generated, only the Project QP has access to the actual database, the rest
of the PREM personnel have read-only copies.
The two databases are clearly defined and distinct and under the control of the
Project QP. The database is checked by two PREM personnel to ensure that all
duplications, missing values, co-ordinate positions, etc. are corrected. The latest
RHA drill hole database (May 2016), and the underground sampling database
(October 2016) were used in the current resource model.
The combined database contains geological, assay, density, collar and survey
information for the drillholes, trenches and the sample section lines. Structural
data, underground survey pegs, channel samples and other valuable data are
recorded. Also included in the database are survey data for the topography and
the quality assurance and quality control (QAQC) data.
28
Bulk Density 8.2.8
Density values were determined by means of a Density Scale onsite using the
weight-in-air and weight-in-water method. A representative half core from each
sample submitted for assay was measured, and in some cases the whole half
core.
For percussion drilling and trench data, no density measurements were taken.
Based on earlier studies, an average bulk density value of 2.8 kg/m3 is assumed
for mineralized samples.
Data Confidence 8.2.9
As stated above, there are two current databases at PREM, the underground
database and the exploration or drill hole database. The confidence for each
database will be described separately.
8.2.9.1 Drill Hole Database
The data is at a relatively good level of confidence for the following reasons -
The database is composed of several generations of data (historical, exploration and trench production data). While visually, the data appears
similar, this is also confirmed by geostatistical comparative studies in previous reports.
The database is stored in Excel spreadsheets which are prone to
inadvertent errors. Some database errors highlighted include duplicates and transposition errors.
The 2012 drillholes have no downhole survey information, although the
rest, including trench data have survey information.
Not all the drillholes are fully logged, just the areas of interest were
sampled and assayed.
Due to the two points above, any resource model generated using this
database can only be classified as an inferred resource.
29
However, it is noted that higher confidence in the data can be achieved by the
following:
A thorough re-log of holes which have un-sampled areas and updating the database.
Where possible, reopen the holes from the 2012 campaign and conduct a
downhole survey.
The data should be in a secure and industry standard database management system in order to satisfy the requirements for a signed-off
Mineral Resource.
8.2.9.2 Underground Database
In the course of 2016, a fundamental flaw was discovered in the underground
database and a decision taken not to have any more confidence in that
database. PREM took the initiative to re-sample the entire underground
operation under strict supervision from the cutting of channels, chip sample
collection and tagging, and industry accepted assaying procedures.
The data is at a high level of confidence for the following reasons –
The entire database has been compiled from May 2016 under strict supervision.
PREM Geological personnel were always present during the cutting,
chipping, bagging and tagging of all samples.
All section lines were surveyed in.
Strict industry accepted assaying procedures were followed, including
QA/QC protocols.
The database is stored in Excel spreadsheets can be prone to inadvertent
errors. Some database errors highlighted include duplicates and transposition errors. However, on the whole, the quality of the data captured is deemed as very good.
Only the PREM QP has access to the database, all others have read-only
copies of the database.
All databases are time stamped and stored on the PREM central database.
30
Quality Assurance/Quality Control 8.2.10
(QA/AQC)
For any report that is reporting resources, quality assurance and quality control
(QAQC) is a necessary requirement for attaching confidence to the mineral
resource and complies with the requirements of the SAMREC (2007) code or
similar industry accepted code of practice.
This QAQC process dictates that a certain amount of blanks, duplicates and
certified reference materials (CRMs) be included in the routine sample assay
process to ensure accuracy and determine the contamination and precision of
the laboratory during the sample preparation and analysis process.
The QAQC procedure has been under the supervision of the Project QP. All
relevant QAQC control charts are shown in Appendix 3.
8.2.10.1 Laboratory
In previous drilling campaigns, RHA have used external laboratories for their
sampling purposes. The QA/QC reports can be seen in previously released
reports , the last being report by Chisonga and Cumming in 2014.
The underground sampling is analysed at the RHA laboratory on site. The
method of analysis is by means of a dual beam analyser.
8.2.10.2 Certified Reference Materials
The CRM material used is supplied by Geostats Pty Ltd. In the past, two CRM
were utilised:
GW 02
GW 03
Currently only the prior is still used, while the latter has been substituted with
Q575 supplied by SGS. Certificates for these materials can be seen in Appendix
3.
31
8.2.10.3 Sampling Routine
The assaying routine employed at RHA laboratory is thus. After every tenth
(10th) sample the following are included:
GW02
Coarse Qz
Fine Qz
Q575
This is repeated until the entire sample run is completed.
Silica blanks, both coarse and milled, were sourced from AMIS, Johannesburg
and tungsten CRM (GW-02) from Geostats, Australia. Large quartzite pebbles
were obtained from a garden nursery and used Updated Resource Report for the
RHA Tungsten Project in the stead of the coarse blanks from AMIS. These were
inserted into the sample stream in a logical sequence in both programmes and
accounted for about 15% of the samples submitted for analysis.
All the blanks returned acceptable value for both drilling campaigns. Therefore, it
is concluded that the data used in the generation of the present Mineral
Resource estimate is free of contamination.
8.2.10.4 Precision
No duplicate samples were submitted.
32
9. Geological Modelling
Compared to the Chisonga & Cumming report of 2014, there has been a
complete overhaul of the geological model. The current model resembles the
model of the late 1970s. The compilation of this model utilises both the drill hole
and underground databases and geological mapping conducted by the author.
The author believes the databases appropriately represent the data and the
quality is considered appropriate for the geological modelling procedures
reported in this document.
9.1 Underground Mapping
In June 2016, an independent underground mapping exercise was conducted on
the underground levels by the author. The primary focus was the Lode 4, but all
other Lodes were mapped too and recorded on level plans.
The geological description of the lodes is mentioned in section 6.2, and this
description can be applied to all the lodes encountered. Each lode can and does
change in lithological appearance every 5m or so. This can be seen in Figure 7.
Lode 4 – 10m from Peg 870-1
33
Lode 4 – 20m from Peg 870-4
Lode 4 – Near Peg 870-6
Figure 7: Underground mapping of Lode 4 - 870 Level
In total, mapping was conducted on the 865, 870, 875 and 884 levels. All
information gathered was then imported into Datamine Studio RM. The author
was then able to generate a 3D model of the respective lodes based on dip, dip
directions and vertical postulations up to and through the 926 level and
ultimately to surface.
This geological model was also supplemented by the underground sampling data
and the drill hole data. The final result is a good correlation that supports/
compliments the mapping conducted in the 1970s.
The extent of the geological model were extended laterally to distances
equivalent to half the drill hole spacing (i.e. ~50m) as allowable for in the
SAMREC (2007) code. Down dip, the model was extended to 100m below the
870 level. This depth was selected as there is a mineralised intersection at this
depth in drill hole RHADD05 to suggest the continuity of the lodes at this depth.
To the north, Lodes 2 & 4 are terminated on the fault. Lodes 5 & 7 are extended
50m to the west beyond the last drill hole data. To the south west, it is postulate
34
that all the lodes are converging, and as such, lodes 5 & 7 are truncated up
against lode 4.
9.1.1 Inter-Lode Mineralisation
From the work conducted during the construction of the current mainstream
wireframes, it was observed that there are good mineral occurrences in
RHADD04 and RHADD05 that were not part of any of these lodes. By geological
inference, one relatively large inter-lode and two minor inter-lodes are now
postulated between Lodes 4 & 5, (Figure 8). The major inter-lode will be referred
to as Lode 4A. The two minor inter-lodes after Lode 4A will be referred to as
Lodes 4B and 4C.
Figure 8: Location of Inter-lodes 4A, 4B and 4C
35
To the east of Lode 2, three more inter-lodes have been postulated via the fact
of good grade intersections on drill holes RHADD005 and RHADD006.
Figure 9: Location of lodes and Inter-lodes east of Lode 2
It can be observed from Figure 9 that Lode 2 HW 2 and Lode 2 HW 4 are not
continuous to depth or laterally. This due to the fact that the high grade
identified on the respective drill hole cannot be conclusively defined elsewhere.
Once more evidence has been determined that the continuity can be confirmed,
those two wireframes defining the inter-lodes will be extended accordingly.
36
9.2 Geological Nomenclature
This geological model has reverted back the original lode naming convention of
the 1970s. The major lodes identified from the underground workings are Lodes
2,4,5,7 and a lode that occurs obliquely to lodes 2 & 4 known as the Splay Lode.
This naming convention only applies to the underground lodes.
Figure 10: Underground Nomenclature for the Lodes
37
9.3 Geological Structures
Geological structures are observed predominantly from the underground
workings are in the form of jointing. The prevalent direction of this jointing
ranges between east-west to north east – south west with a dip of 45-55o south.
Structural fault observations were limited. The most prominent fault that has a
direct impact on the understanding of the geological setting is encountered twice
at RHA. The first observation point is in the open pit, and the second is at the
north end of the lode 4 - 870 level drive. From these two observations, a fault is
now postulated in a north east – south west direction dipping ~75o to the north.
The significance of this observation is that in previous models, there was a
theory that the lodes were continuous from the underground workings to the
open pit. It is now considered that with the orientation of this fault that is
probably not the case anymore. As such, the underground and open pits are
modelled separately.
A second fault found in the lode 5 - 870 level north drive has a similar strike and
but shallower dip. The effect of this fault is unknown.
9.4 Open Pit Mapping
It has been stated in previous reports that the opinion was the lodes were
traceable from the underground workings and surface outcrops into the open pit
area).
The opinion now is that the fault, now confirmed in a holing in the pit and the
870 level, does break that continuity, (Figure 11). Therefore the occurrence of
the mineralisation in the open pit area has to be considered as being
independent to the underground workings.
38
Figure 11: Location of the fault plane in the pit
In 2012/ 2013, a series of trenches were dug in the open pit area and described
by the Qualified Person (Mr B. Cumming). The logs for these trenches can be
seen in the Appendix of the Chisonga Cumming resource report of 2014.
It is apparent mineralisation occurrences are not continuous, but rather have a
lensoidal character in nature. Secondly, the trenches were sampled and assayed
in their entirety and it is obvious that the tungsten mineralisation is not
necessary restricted to the expected mineralised zones.
The opinion of the author to try generating wireframes for the open pit area
would not be practical due to the aspects mentioned above. The decision was
made to generate a predictive block model to:
a. Generate a model that predicts the mineralisation occurrence,
b. To estimate a grade into that model.
From observations in the pit, the strike is consistently east – west, dipping 65-
70o north.
39
9.4.1 Mineralised Wireframe for the
Open Pit
The generation of the block model origin and proto-block model will be described
in Section 10. The open pit data consisting of drill hole and trench data, was
flagged based on grade above (FLAG 1) and below (FLAG 0) on a cut-off grade
of 0.5kg/t WO3.
Search parameter files were constructed based on the known dip and strike and
a search distance of 75m in the orientated X & Y planes and 0.5m in the Z plane.
By using Studio RM, an estimation process using the Nearest Neighbour, created
a block model with cells coded either 1 or 0. All cells coded with the value of 1
are the considered to be part of the mineralised envelope. Then using a process
in Studio RM, a wireframe is created around those cells that best represents the
mineralised envelope, (Figure 12).
Looking South East
40
Looking East
Figure 12: Shape of the mineralisation on the open-pit
41
10 Geostatistical Analysis
The geostatistical analysis of the respective mineralised zones will be reported in
three parts:
Underground Lodes
Open Pit
Inter-load Mineralisation
The geostatistical analysis for this report is determined from a combination of
the underground sampling and the drill hole databases. Due to lack of data
availability on some of the Lodes, historical data will be considered. This will be
made mentioned for those respective lodes.
10.1 Underground Geostatistical Analysis
The major lodes described here will be Lodes 2,4,5,7 and the Splay Lode.
10.1.1 Lode 2
Historically, Lode 2 has been the most extensively mined lode. It has been
exploited from the current 865 level right up to surface. However, there is a
Lode 2 potential below the 865 level.
The data sourced for this lode comes from the underground sampling (865_001C
to 865_053C) and the drill intersections listed in Table 4.
42
Table 4: Drill hole intersects into Lode 2
10.1.2 Lode 4
Lode 4 is currently the lode of interest from a mining perspective and hence has
the majority of the underground sampling database assigned to it. Chip sampling
has been completed on the 870 level (870_001C to 870_155C), the 875 level
(875_001C to 875_016C) and the 884 level (884_001C to 884_075C) for a total
of 238 section lines.
The drill hole intersections are listed in Table 5.
Table 5: Drill hole intercepts into Lode 4
43
10.1.3 Lode 5
Lode 5 is the ore lode that outcrops in the old quarry. It was substantially mined
from surface to the 926 level, but not much is known about the lode below 926.
Geological modelling indicates that it intersects the 870 level where the current
waiting place is now located.
This lode has not been sampled in the latest sampling campaign, therefore the
sample data available for this lode are the drill hole intersections, four in total,
(Table 6).
Table 6: Drill hole intercepts into Lode 5
44
RHA has in its possession a data plan that Falconbridge compiled of Lode 5 at
this intersection on the 870 level, (Figure 13). There is no supporting
documentation or QA/QC reports to confirm that this sampling deemed valid, but
it can be used as a guideline in an inferred resource only.
There are 15 samples, and the average grade for these is 0.93kg/t over an
average of 1.37m
Figure 13: Falconbridge sampling of Lode 5
10.1.4 Lode 7
Lode 7 has been substantially sampled on the 870 level, (870_157C to
870_284C), a total of 127 sample sections.
The balance of the data for Lode 7 is made up from the drill hole intersections
are listed in Table 7.
45
Table 7: Drill hole intercepts into Lode 7
10.1.5 Splay Lode
As mentioned in Section 8.2, the Splay Lode intersects the Lodes 2 & 4 at about
a 60o angle. Sampling for this lode is located on the 870 level (870_93C to
870_100C and 870_701C to 870_715C) and the 884 level (884_056C to
884_060C).
There is no drill hole intersects into this lode.
10.1.6 Geostatistical Analysis
10.1.6.1 Basic or Raw Geostatistical Analysis
Basic or ‘naïve’ geostatistical analysis was conducted on all the lodes mentioned
in the sections above, which included the underground sampling and the drill
hole data. This analysis of the raw, uncomposited data can be seen in Table 8.
The statistics below are only based on verified data. No Falconbridge data is
included.
46
Table 8: Basic Statistics of the Lodes
Histograms for the raw data analysis can be seen in Figure 14.
47
48
Figure 14: Histograms for the respective lodes
10.1.6.2 Composite Data Geostatistical Analysis
The cumulative histogram of sample length is presented in Figure 15.
Approximately 97% of the samples were at or less than 1m in length.
Underground observations indicate that the maximum channel width observed
was around 1.5m. Therefore all samples were composited to a length of 1.5m.
49
Figure 15: Cumulative histogram of sample lengths
Statistics was then carried out on the composited database and are presented in
Table 9.
Table 9: Statistics of composited data
Due to the nature of a tungsten ore body, it was decided not to apply any form
of capping to the WO3 data. From testing conducted it was concluded that by
applying a cap, the mean tends to decrease too much, thus potentially
underestimate to ore body. The CoV values observed for each lode are slightly
on the higher side, but the opinion is that they will not have a material impact.
10.1.6.3 Grade Indications from Falconbridge Data
The Falconbridge data is available to RHA in the form of scanned sheets, either
in the form on plan or longitudinal sections, Figure 16. There is no accompanying
QA/QC validations and there sample pulps also not available.
50
Figure 16: Example of Falconbridge sample data
The purpose of considering the statistics from this database is for comparison
purposes only. In the case of Lode 2, this lode was mined extensively from 865
level upwards. Currently, there is limited verified data for Lode 2, but this
Falconbridge data could give a better understanding of the Lode 2 potential
below the 865 level as it was extensively mined above this level. The table below
tabulates the available Falconbridge data.
Table 10: Statistics of available Falconbridge data
51
10.2 Inter-lode Geostatistical Analysis
The raw statistics for the defined inter-lodes are presented in Table 11. These
represent the high grade intersections that are not assigned to the major lodes
mentioned above. In constructing the respective wireframes, RHA personnel
looked for lateral continuity with other drill holes and visible intersections on the
926 and 870 levels.
Table 11: Basic statistics of the inter-lodes
10.3 Open Pit Geostatistical Analysis
To define this area, the open pit area is considered to that part of the operation
that occurs in and around the previous optimised pit shell to a depth of 200m
below surface. Data is excluded if it is known it form part of the underground
operation.
Due to the process described in Section 8.4.1, the basic geostatistics will be
tabulated as per the predictive model, presented in Table 12:
Code = 1 : WO3>0.5kg/t
Code = 0 : WO3<0.5kg/t
Table 12: Raw statistics of the open-pit data
Histograms for the open pit data can be seen in Fig 17.
52
Figure 17: Histograms of the open-pit data
53
10.4 Variography Analysis
In most estimation model runs, Ordinary Kriging (OK) is the preferred method of
estimation. In order to conduct an OK estimation, a variogram of the data has to
be constructed. A variogram is a function of the distance and direction
separating two locations that is used to quantify dependence. The variogram is
defined as the variance of the difference between two variables at two locations.
10.4.1 Underground Lodes Variograms
Considering the amount of data available on the current underground lodes, only
Lode 4 was able to generate any reasonable variogram. The other lodes (lodes
2,5,7 and splay) do not have enough data points or only data in one direction.
10.4.1.1 Lode 4 Variogram
A variogram analysis was undertaken on the Lode 4 data to develop a suitable
variogram. Experimental variograms were run using different lag distances, (5m,
10m, 20m, 25m), it was determined that the experimental variogram with the
15m lag was best suited. The experimental variogram was fitted using Studio
RM, this variogram can be seen in Figure 18.
Long Axis
54
Short Axis
Down Hole
Figure 18: Variography of Lode 4
The summary of the Lode 4 variography can be seen in Table 13.
Table 13: Summary of Lode 4 variography
55
10.5 Open-Pit Variography
A variogram analysis was undertaken on the Open Pit data to develop a suitable
variogram. Two sets of experimental variograms were run, one on the data
above 0.5kg/t WO3 and the second one on data below 0.5kg/t WO3. These
experimental variograms were also conducted using different lag distances, (5m,
10m, 20m, 25m), it was determined that the experimental variogram with the
10m lag was best suited for both experimental variograms. The experimental
variogram was fitted using Studio RM, this variogram can be seen in Figs. 19 &
20.
Long Axis
56
Short Axis
Figure 19: Variography of open pit data above 0.5kg/t cut-off
Long Axis
57
Short Axis
Figure 20: Variography of open pit data below 0.5kg/t cut-off
10.6 Search Parameter Files
The ranges of continuity obtained from the variogram modelling of Lode 4
(underground) and the Lodes in the open pit were used as a guide to the search
parameter search files and multiple search passes were used (Table 14 & 15).
The search ellipse was oriented according to the direction of maximum continuity
with rotation angles.
Dynamic search was employed to fill all the blocks, with a second search (SVOL
= 2) exaggerated to 2 and the third search (SVOL = 3) exaggerated to 5. The
minimum and maximum number of samples employed in the first search was 10
and 20, respectively. For the second and third search volumes, this was 5 and
20 as well as 1 and 20, respectively. The search distances can be seen in Tables
14 &15.
The underground lodes that do not have an associated variogram, were
orientated according to the strike and dip of their wireframe.
58
Table 14: Summary of underground lodes search parameters
Table 15: Summary of open pit search parameters
59
10.7 Estimation Parameter Files
The estimation parameters used to generate the respective resource models are
described in Table 16.
Table 16: Estimation Parameter file descriptions
60
11 Resource Block Model
11.1 Model Origin
The block model origin was determined in order to cover the entire project area
that includes the underground and open pit areas. The Table 17 referring to all
model origin points is below. An orthogonal model was constructed.
Table 17: Block Model Origin
11.2 Block Models
Longitudinal section of the respective block models can be viewed in Appendix 3.
The figures below illustrate the Lode 4 grade and resource classification models.
Figure 21: Lode 4 Grade Model
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Figure 22: Lode 4 Resource Classification
11.3 Model Validation
Three forms of validation were carried out by the author, namely:
Visual Inspection
o Direct comparison to sample data to block model
Kriging Efficiencies
o This is determined by using the formula:
Block Variance (BV) = Sill – Kriging Variance.
o Then Kriging Efficiency (KE) = (BV-Kriging Varience) / (BV)
o If the BV is less than 0.5, then that block cell will be classified at a
lower confidence level.
Slope of Regression
o This is determined by using the formula:
SR= (BV-KE + Le Grange) / (BV-KE + (2*Le Grange))
o If the SR is less than 0.75, then that block cell will be classified at
a lower confidence level.
Swath Plot Analysis
o This is a visual comparison of input grade sample to estimated
resource blocks.
o A Swath plot analysis of all block models can be seen in Appendix 1
62
QQ Plot
o This plot tests the ‘goodness of fit’ between the input data and the
estimated block model.
o The QQ plots can be seen in Appendix 2
o Table 18 presents the Correlation Coefficients of the sample data
to the resource model.
Table 18: Correlation Coefficients
63
12 Mineral Resource Statement
As the respective resource models are validated, a grade tonnage calculation is
generated for each. At the time of this report, no specific cut-off grade is
stipulated as the extraction process could require everything from a zero (0kg/t)
cut-off.
12.1 Underground Resources
12.1.1 Lode 2
The grade tonnage calculation for Lode 2 are presented in Figures 23 & 24.
Figure 23: Lode 2 Indicated Resource
64
Figure 24: Lode 2 Inferred resource
Cognisance should be taken of the fact that due to the limited amount of data,
the potential Lode 2 Inferred resource might be understated. From the
Falconbridge data, that is indicating a potential average grade of 5.6kg/t WO3.
12.1.2 Lode 4
The grade tonnage calculation for Lode 4 are presented in Figures 25, 26 & 27
65
Figure 25: Lode 4 Measured Resource
Figure 26: Lode 4 Indicated Resource
66
Figure 27: Lode 4 Inferred Resource
12.1.3 Lode 5
The grade tonnage calculation for Lode 5 is presented in Table 19. Lode 5 is not
well supported with sampling, therefore only an inferred resource can be
postulated.
Table 19: Grade and Tonnages for Lode 5
67
12.1.4 Lode 7
The grade tonnage calculation for Lode 7 are presented in Figures 28 & 29
Figure 28: Lode 7 Indicated Resource
Figure 29: Lode 7 Inferred Resource
68
12.1.5 Splay Lode
The grade tonnage calculations for Slay Lode are presented in Figs 30 & 31.
Figure 30: Splay Lode Indicated Resource
Figure 31: Splay Lode Inferred Resource
69
12.1.6 Inter-lode 4A
The grade and tonnage for Inter-Lode 4A is presented in Table 20.
Table 20: Grade and Tonnage of Inter-Lode 4A
12.1.7 Inter-lodes 4B & 4C
The grade and tonnage for Inter-Lode 4B & 4C is presented in Table 21.
Table 21: Grade and Tonnage of Inter-Lodes 4B & 4C
12.1.8 Inter-lode Lode 2 HW1
The grade and tonnage for Inter-Lode 2 HW1 is presented in Table 22.
Table 22: Grade and Tonnage of Inter-lode 2 HW1
70
12.1.9 Inter-lode Lode 2 HW2
The grade and tonnage for Inter-Lode 2 HW2 is presented in Table 23.
Table 23: Grade and Tonnage for Inter-Lode 2 HW2
12.1.10 Inter-lode Lode 2 HW3
The grade and tonnage for Inter-Lode 2 HW3 is presented in Table 24.
Table 24: Grade and Tonnage for Inter-Lode 2 HW3
12.1.11 Inter-lode Lode 2 HW4
The grade and tonnage for Inter-Lode 2 HW4 is presented in Table 25.
Table 25: Grade and Tonnage for Inter-Lode 2 HW4
71
12.2 Open Pit Resources
The grade tonnage calculations are presented in Table 32, 33 and 34.
Figure 32: Open Pit Grade-Tonnage Graph (Total)
Figure 33: Open Pit Indicated Resource
72
Figure 34: Open Pit Inferred Resource
12.3 Open Pit Inventory
The current mining plans plan to exploit the open pit down to a depth of ~900
A.M.S.L. The 2012 and 2013 drilling campaigns have intersected mineralisation
below this level, so the mineral inventory of the mineralisation down to a depth
of 775 A.M.S.L is shown in Figure 35.
At the time when a credible mining plan is in place to exploit this ore, it can
easily be upgraded to a higher resource category.
73
Figure 35: Inventory of mineralisation below the open pit to 735 A.M.S.L.
12.4 Resource Statement Summary
A summary of all the resources are tabulated below in Table 26. They are
presented at a 0kg/t cut-off due to the mineral extraction process that will be
employed at RHA.
74
Table 26: Summary of RHA Grades and Tonnages
Lode Resource Category
Below Level
Tonnes Metal
Content (kg)
WO3 Grade (kg/t)
2 Indicated 865 2,081 2,767 1.33
2 Inferred 865 97,964 264,504 2.70
4 Measured 926 21,912 78,665 3.59
4 Indicated 926 38,961 169,478 4.35
4 Total 60,873 248 0.00
4 Inferred 926 180,107 828,491 4.60
5 Inferred 926 166,883 417,208 2.5
7 Indicated 926 16,168 13,151 0.81
7 Inferred 926 155,508 113,003 0.73
Splay Inferred 926 41,602 265,005 6.37
4A Inferred 926 106,114 397,966 3.75
4B Inferred 926 15,351 68,025 4.43
4C Inferred 926 17,464 118,607 6.79
2 HW1 Inferred 926 243,434 1,562,235 6.42
2 HW2 Inferred 926 29,308 34,877 1.19
2 HW3 Inferred 926 108,871 947,315 8.70
2 HW4 Inferred 926 25,427 109,845 4.32
Open Pit Indicated 707,248 1,039,655 1.47
Open Pit Inferred 2,460,120 3,714,781 1.51
Total Measured Indicated
U/G 79122 264,061 3.34
Open Pit 707248 1,039,655 1.47
Total Inferred
U/G 1188033 5,127,079 4.32
Open Pit 2460120 3,714,781 1.51
75
13 Conclusion
In line with the project scope, PREM has generated a revised geological and
resource models for the RHA Tungsten Project.
The geological model is made up five ‘major’ lodes and seven inter-lodes. The
lodes 2 and 4 are generally striking north west – south east and dipping towards
the east at 70-75o. The lodes 5 & 7 are roughly east-west trending with sub-
vertical dip (equivalent to 75-85°). The ore in the open pit is similar to lodes 5 &
& 7, but these dip at ~75o to the north.
The geological and resource models are based on an updated and verified
database composed of the previous drilling campaigns and a new underground
database. Based on drill hole intersections, the underground wireframes have
been extended down 100m below 870 level, and 75m laterally.
The resource model has been declared on all underground and open pit material.
Only Lode 4 has satisfied the requirements to have a portion of the resources
classified into the Measured Resource category. Other lodes do have some
indicated resource, but the majority of the lodes are classified as inferred. All
tonnages and grade are reported from below the 926 level. Only Lode 2 is
reported from below the 865 level.
PREM is satisfied with the quality of the data and database used in the geological
and resource modelling processes. There are no material issues that affect the
confidence of the Resource Classification at this time. It is recognised that more
drilling is required to improve the resource classification of certain lodes and all
the inter-lodes.
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14 CERTIFICATE OF DISCLOSURE
The information in this report that relates to the Mineral Resource is based on
information compiled and verified by the Competent Person, Bruce Cumming
(Pr.Sci.Nat). The Competent Person has sufficient experience which is relevant
to the style of mineralisation and types of deposits under consideration, and to
the activity which has been undertaken, to qualify as a Competent or Qualified
Person as defined by the 2011 edition of the Canadian National Instrument (NI
43-101) Standards of Disclosure for Mineral Projects, 2004 edition of the
Australasian Code for Reporting of Exploration Results, Mineral Resources and
Ore Reserves (JORC), as well as the 2007 edition of the South African Code for
Reporting of Exploration Results, Mineral Resources and Mineral Reserves
(SAMREC).
Capacity and Independence
PREM prepared this report, under the guidance of Bruce Cumming, and it is
signed off according to SAMREC & JORC. Bruce Cumming is a shareholder in
Premier African Minerals Ltd (PREM).
Scope of Work/Materiality
This resource statement is based on:
o Sampling Information gathered at RHA;
o Underground and open-pit geological mapping;
o Previous work undertaken on this project
All source data was reviewed and verified. PREM has endeavoured to ensure that
no error of fact is contained within this statement. Any such error is not
intentional and is not a deliberate effort to mislead.
Risks
The business of mining and mineral exploration, development and production by
their nature contain operational risks. The business depends upon, amongst
other things, successful prospecting programs and competent management.
Profitability and asset values can be affected by unforeseen changes in operating
circumstances and technical issues.
77
Factors such as political and industrial disruption, currency fluctuation,
commodity prices and interest rates could have an impact on the project’s future
operations, and potential revenue streams can also be affected by these factors.
The majority of these factors are, and will be, beyond the control of any
operating entity.
____________________________
Bruce Cumming
BSc. Hons (Geology), Pri.Sci.Nat., GSSA
78
15 Appendix 1
Swath Plot Analysis
79
Underground Lodes
80
Figure 36: Appendix 1 – Underground Swath Plots
81
Open Pit
Figure 37: Appendix 1 - Open Pit Swath Plot
82
16 Appendix 2
QQ Plots
83
84
85
Figure 38: Appendix 2 - QQ Plots
17 Appendix 3
Block Model Longitudinal Sections
86
Figure 39: Appendix 3 - Lode 2 Longitudinal Sections
87
Figure 40: Appendix 3 - Lode 4 Longitudinal Sections
88
Figure 41: Appendix 3 - Lode 7 Longitudinal Sections
89
Figure 42: Appendix 3 - Splay Lode Longitudinal Sections
90
18 Appendix 4
QA/QC Certificates and Control Graphs
91
92
Certificate of verification from SGS of Q0575
93
Batch Analysis using GW02
Figure 43: Appendix 3 - QA/QC CRM Certificates and Analysis
94
