structural geology Mineral Resources

8/13/2019 structural geology Mineral Resources

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Chapter 15Riches in Rock:

Mineral Resources

Earth: Portrait of a Planet, 4th editionby Stephen Marshak 2011 W.W. Norton & Company

PowerPoint slides prepared by Ronald L. Parker, Fronterra Geosciences, 700 17 th Street, Suite 900, Denver, CO, 80202

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Riches in Rock: Mineral ResourcesRiches in Rock: Mineral ResourcesRiches in Rock: Mineral ResourcesRiches in Rock: Mineral Resources

Preparedby:Preparedby:

Ronald L. ParkerRonald L. Parker,, Senior GeologistSenior Geologist

Fronterra Geosciences,Fronterra Geosciences,

Denver, ColoradoDenver, Colorado

Earth: P ortrait of a Planet, 4th edition, by Stephen Marshak 2011, W. W. NortonEarth: P ortrait of a Planet, 4th edition, by Stephen Marshak 2011, W. W. Norton Chapter 15: Riches in Rock: Min eral ResourcesChapter 15: Riches in Rock: Min eral Resources


IntroductionIntroduction

Quest for mineral resources has a rich human history.Quest for mineral resources has a rich human history.

Native American copper trade, Spanish conquistadors.Native American copper trade, Spanish conquistadors.

California and Klondike Gold Rushes.California and Klondike Gold Rushes.

Fig. 15.1


Mineral ResourcesMineral Resources

Two major categories.Two major categories.

MetallicMetallic

GoldGold

SilverSilver

CopperCopper

LeadLead

ZincZinc

IronIron

AluminumAluminum

NonmetallicNonmetallic

Sand and gravelSand and gravel

GypsumGypsum

HaliteHalite

Dimension stoneDimension stoneFluorite cleavage octahedra


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What Is a Metal?What Is a Metal?

Opaque, shiny, smooth, conductive solids.Opaque, shiny, smooth, conductive solids.

Metal properties derive from metallic chemical bonds.Metal properties derive from metallic chemical bonds.

Delocalized electrons move from atom to atom easily.Delocalized electrons move from atom to atom easily.

Electron fluidity renders metals electrically conductive.Electron fluidity renders metals electrically conductive.

The pins on this computer processor are coated with a thin layer of gold.


What Is a Metal?What Is a Metal?

Not all metals behave the same way.Not all metals behave the same way.

Metal properties are due to bond type and structure.Metal properties are due to bond type and structure.

Metals may be extremely hard (titanium) or soft (copper).Metals may be extremely hard (titanium) or soft (copper).

DuctileDuctileable to be drawn into thin wires.able to be drawn into thin wires.

MalleableMalleableable to be hammered into thin sheets.able to be hammered into thin sheets.

Fig. 15.2


The Discovery of MetalsThe Discovery of Metals

Native metals occur naturally in a pure form.Native metals occur naturally in a pure form.

GoldGold

SilverSilver

CopperCopper

IronIron

People have utilized native metals for thousands ofPeople have utilized native metals for thousands ofyears.years.

ToolsToolseasily shaped by cold working.easily shaped by cold working.

MoneyMoneyrare and durable.rare and durable.Fig. 15.3b


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We use minerals thatWe use minerals that containcontain metals.metals.

Metal ions are bonded to nonmetallic elements.Metal ions are bonded to nonmetallic elements.

MetalMetal--bearing minerals seldom resemble the pure metal.bearing minerals seldom resemble the pure metal.

Fig. 15.2Malachite, a copper ore mineral Copper metal



Three principal metals todayThree principal metals todaycopper, iron, andcopper, iron, andaluminum.aluminum.

Copper used first (4000Copper used first (4000 B.C.EB.C.E.)..).

Smelting Cu sulfides is easiest.Smelting Cu sulfides is easiest.

Copper was too soft for good tools or weapons.Copper was too soft for good tools or weapons.

The Sumerians discovered bronze (~2800The Sumerians discovered bronze (~2800 B.C.E.B.C.E.).).

Copper alloyed with tin.Copper alloyed with tin.

Bronze is stronger than either metal alone.Bronze is stronger than either metal alone.



Iron is superior to copper or bronze.Iron is superior to copper or bronze.

StrongerStronger

HarderHarder

More abundantMore abundant

Iron is much harder to smelt, however. It requires:Iron is much harder to smelt, however. It requires:

Much higher temperatures.Much higher temperatures.

Chemical reaction with carbon monoxide (CO).Chemical reaction with carbon monoxide (CO).

CO is derived from burning with charcoal.CO is derived from burning with charcoal.


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Smelting, discovered by an unknown prehistoric genius?Smelting, discovered by an unknown prehistoric genius?

Smelting releases metals from ore minerals.Smelting releases metals from ore minerals.

Different minerals require:Different minerals require:

Different smelting techniques.Different smelting techniques.

Different temperatures.Different temperatures.

Nonmetallic waste is called slag.Nonmetallic waste is called slag.

Fig. 15.4a


SteelSteeliron smelted with carbon.iron smelted with carbon.

Blending metals creates alloys.Blending metals creates alloys.

Alloys are unlike pure metals.Alloys are unlike pure metals.

BronzeBronzealloy of copper and tin.alloy of copper and tin.

BrassBrasscopper alloyed with zinc.copper alloyed with zinc.


Fig. 15.4b


There are 63 or so metals used in our modern world.There are 63 or so metals used in our modern world.

Precious metalsPrecious metalsgold, silver and platinum.gold, silver and platinum.

Base metalsBase metalscopper, lead, zinc, and tin.copper, lead, zinc, and tin.

Before 1700, only nine metals were in use.Before 1700, only nine metals were in use.

Au, Cu, Ag, Hg, Pb, Sn, Sb, Fe, and As.Au, Cu, Ag, Hg, Pb, Sn, Sb, Fe, and As.



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Rock withRock withmetalmetal--rich minerals.rich minerals.

Concentrated enough to beConcentrated enough to be

economic to mine.economic to mine.

Metal must be readilyMetal must be readily

extracted from the mineral.extracted from the mineral.

Many different ore minerals.Many different ore minerals.

Many are sulfides or oxides.Many are sulfides or oxides.

Often colorful minerals.Often colorful minerals.

What Is an Ore?What Is an Ore?

Fig. 15.5b


Ores are not uniformly distributed through Earths crust.Ores are not uniformly distributed through Earths crust.

Geologic processes concentrate metals into deposits.Geologic processes concentrate metals into deposits.

Concentration must be high enough to yield a profit.Concentration must be high enough to yield a profit.

The amount of useful metal present is the ore grade.The amount of useful metal present is the ore grade.

Different ores occur in different geologic settings.Different ores occur in different geologic settings.

What Is an Ore?What Is an Ore?

Fig. 15.6


How Do Ore Deposits Form?How Do Ore Deposits Form?

Ores form via geological processes.Ores form via geological processes.

Magmatic activity.Magmatic activity.

Hydrothermal alteration.Hydrothermal alteration.

Secondary enrichment.Secondary enrichment.

Groundwater transport (MVT).Groundwater transport (MVT).

Sedimentary processes.Sedimentary processes.

Residual weathering.Residual weathering.

Hydraulic sorting.Hydraulic sorting.

Fig. 15.5a


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Magmatic depositsMagmatic depositsfrom a cooling plutonic intrusion.from a cooling plutonic intrusion.

Sulfide minerals crystallize early and sink in magma.Sulfide minerals crystallize early and sink in magma.

Form massive sulfide ores at the bottom of chamber.Form massive sulfide ores at the bottom of chamber.

Sulfides include:Sulfides include:

Pyrite.Pyrite.

Chalcopyrite.Chalcopyrite.

Galena.Galena.

Fig. 15.7aFig. 5.11c



Hydrothermal depositsHydrothermal depositshot, chemically active water.hot, chemically active water.

Hot fluid leaches metal ions out of rock near plutons.Hot fluid leaches metal ions out of rock near plutons.

Minerals precipitate in lower P and T locations.Minerals precipitate in lower P and T locations.

Occur disseminated through intrusion or in veins.Occur disseminated through intrusion or in veins.

Fig. 15.7b,c



Hydrothermal depositsHydrothermal depositsfound near midfound near mid--ocean ridges.ocean ridges.

Black smokersBlack smokersoccur along all midoccur along all mid--ocean ridges.ocean ridges.

Seawater in cracked, hot crust is heated, leaching metals.Seawater in cracked, hot crust is heated, leaching metals.

Hot water hits the cold ocean and metals crystallize out.Hot water hits the cold ocean and metals crystallize out.

Fig. 15.7dFig. 4.5b


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SecondarySecondary--enrichment depositsenrichment depositsadds Oadds O22, OH, and CO, OH, and CO22..

Groundwater leaches and oxidizes primary sulfide ores.Groundwater leaches and oxidizes primary sulfide ores.

The secondary deposit often has beautiful minerals.The secondary deposit often has beautiful minerals.

MalachiteMalachite

AzuriteAzurite

TurquoiseTurquoise

Fig. 15.8



Mississippi ValleyMississippi ValleyType (MVT) ores.Type (MVT) ores.

Orogenic belts squeegee hot water through deep basins.Orogenic belts squeegee hot water through deep basins.

The hot water leaches minerals and carries them along.The hot water leaches minerals and carries them along.

Where basin brines surface and cool, they deposit metals.Where basin brines surface and cool, they deposit metals.

From leadFrom lead--zinc (Pbzinc (Pb--Zn) deposits in the Mississippi Valley.Zn) deposits in the Mississippi Valley.



Sedimentary depositsSedimentary depositsform under special conditions.form under special conditions.

Banded iron formations (BIFs).Banded iron formations (BIFs).

Layered gray iron oxides and red chert (jasper).Layered gray iron oxides and red chert (jasper).

Formed from 2.5Formed from 2.51.8 Ga from O1.8 Ga from O22 buildup in the atmosphere.buildup in the atmosphere.

Manganese (MnOManganese (MnO22rich) nodules.rich) nodules.

Rich in trace elements, these grow slowly on the seaRich in trace elements, these grow slowly on the sea--floorfloor

Fig. 15.9


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Residual mineral depositsResidual mineral depositsrainy tropical settings.rainy tropical settings.

Form via extreme chemical weathering in wet tropics.Form via extreme chemical weathering in wet tropics.

Intense weathering strips almost everything out of soil.Intense weathering strips almost everything out of soil.

The residual soil is enriched in Fe and Al oxides.The residual soil is enriched in Fe and Al oxides.

BauxiteBauxiteprimary ore of aluminum.primary ore of aluminum.

Fig. 15.10



Hydraulic sortingHydraulic sortingplacer deposits from flowing water.placer deposits from flowing water.

In high velocity water:In high velocity water:

Low density minerals are suspended and washed away.Low density minerals are suspended and washed away.

HighHigh--density grains are concentrated by settling out.density grains are concentrated by settling out.

Important for gold, tin, and iron.Important for gold, tin, and iron.

Best preserved in fossilBest preserved in fossil

stream sediments.stream sediments.

Ore source can beOre source can be

traced upstream.traced upstream.

Fig. 15.11


Where Are Ore Deposits Found?Where Are Ore Deposits Found?

Tectonic processes are a dominant control.Tectonic processes are a dominant control.

Igneous and hydrothermal activity occur:Igneous and hydrothermal activity occur:

At plate boundaries.At plate boundaries.

Along rifts.Along rifts.

At hot spots.At hot spots.

Tectonic effects are overprinted by the hydrologic cycle.Tectonic effects are overprinted by the hydrologic cycle.


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OpenOpen--pit miningpit miningshallow ore bodies.shallow ore bodies.

Less expensive and dangerous than tunnel mines.Less expensive and dangerous than tunnel mines.

Usually require ore within 100 m of the land surface.Usually require ore within 100 m of the land surface.

OpenOpen--pit mining creates large excavations.pit mining creates large excavations.

Rock is broken by explosives and removed for processing.Rock is broken by explosives and removed for processing.

Ore metal is concentrated by treatment or smelting.Ore metal is concentrated by treatment or smelting.

Waste rock is stored in giant tailings piles.Waste rock is stored in giant tailings piles.

Ore Exploration and ProductionOre Exploration and Production

Fig. 15.12d


Ore Exploration and ProductionOre Exploration and Production

Underground minesUnderground minesore is obtained by tunneling.ore is obtained by tunneling.

Tunnels or vertical shafts are excavated.Tunnels or vertical shafts are excavated.

Ore is loosened by blasting and hauled to the surface.Ore is loosened by blasting and hauled to the surface.

Underground mines are expensive and dangerous.Underground mines are expensive and dangerous.

Tunnel collapses.Tunnel collapses.

Poisonous and explosive gases.Poisonous and explosive gases.

Fig. 15.12b


Society uses many materialsSociety uses many materials

that dont contain metals.that dont contain metals.

Called industrial minerals.Called industrial minerals.

Dimension stone.Dimension stone.

Crushed stone/concrete.Crushed stone/concrete.

Other materials.Other materials.

Nonmetallic Mineral ResourcesNonmetallic Mineral Resources


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Dimension stoneDimension stonerock slabs used as building material.rock slabs used as building material.

Rock is used for visual appeal and durability.Rock is used for visual appeal and durability.

Requires that rock with special properties be carefully cut.Requires that rock with special properties be carefully cut.

Special type of quarrying tools and personnel.Special type of quarrying tools and personnel.

Cut and polished rock slabs are highly prized.Cut and polished rock slabs are highly prized.


Fig. 15.13a



Crushed stone (aggregate) is used for many purposes.Crushed stone (aggregate) is used for many purposes.

Forms the foundation for all roads and railways.Forms the foundation for all roads and railways.

Raw material for cement, concrete, and asphalt.Raw material for cement, concrete, and asphalt.

Used extensively in the modern world.Used extensively in the modern world.

Chapter 15 Opener



Many nonmetallic minerals are common in homes.Many nonmetallic minerals are common in homes.

CalciteCalcitebase material of cement and concrete.base material of cement and concrete.

ClayClaybricks, pottery, porcelain, and other ceramics.bricks, pottery, porcelain, and other ceramics.

GypsumGypsumwallboard and plaster.wallboard and plaster.

QuartzQuartzused to make window glass.used to make window glass.

Rare earth elements (REEs)Rare earth elements (REEs)highhigh--tech applications.tech applications.

Fig. 15.14


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How Long Will Resources Last?How Long Will Resources Last?

World demand for mineral resources is enormous.World demand for mineral resources is enormous.

Industrialized countries consume vast quantities.Industrialized countries consume vast quantities.

In the U.S. we use 4 billion tons of geologic materials/year.In the U.S. we use 4 billion tons of geologic materials/year.

Requires moving 18 billion tons of material.Requires moving 18 billion tons of material.

This is ~95x the annual sediment moved by the Mississippi.This is ~95x the annual sediment moved by the Mississippi.

Fig. 15.15



Mineral resources are nonrenewable, like coal and oil.Mineral resources are nonrenewable, like coal and oil.

They form as the result of geologic processes.They form as the result of geologic processes.

These processes are too slow to generate new deposits.These processes are too slow to generate new deposits.

Thus, once mined, mineral resources are gone forever.Thus, once mined, mineral resources are gone forever.



We have calculated reserves for mineral resources.We have calculated reserves for mineral resources.

We can estimate the expected lifetime of resources.We can estimate the expected lifetime of resources.

Consumption rates.Consumption rates.

Reserve amounts.Reserve amounts.

Some mineral resourcesSome mineral resources

are running out.are running out.

New technologies mayNew technologies may

extend these lifetimes.extend these lifetimes.


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Continued use of scarce minerals will require:Continued use of scarce minerals will require:

Discovery of new sources.Discovery of new sources.

Increase in price to make hardIncrease in price to make hard--toto--get reserves profitable.get reserves profitable.

Increased efficiency and conservation.Increased efficiency and conservation.

Substitution.Substitution.

Recycling.Recycling.

Doing without.Doing without.


Mineral resources are unevenly distributed.Mineral resources are unevenly distributed.

Dependent upon the geologic history of a region.Dependent upon the geologic history of a region.

Trade is needed to meet imbalances.Trade is needed to meet imbalances.

Many wars have roots in mineral resource imbalances.Many wars have roots in mineral resource imbalances.

Strategic minerals are a particularly sensitive topic.Strategic minerals are a particularly sensitive topic.

Metals needed for national security and defense.Metals needed for national security and defense.

ManganeseManganese

PlatinumPlatinum

ChromiumChromium

CobaltCobalt

Rare earth elements haveRare earth elements have

become important inbecome important in

in recent years.in recent years.



Mining and the EnvironmentMining and the Environment

Mineral extraction and processing leaves a big footprint.Mineral extraction and processing leaves a big footprint.

OpenOpen--pit mines are large scars on the landscape.pit mines are large scars on the landscape.

Mining creates huge volumes of waste tailings.Mining creates huge volumes of waste tailings.

Tailings piles are often acidic and laden with toxic metals.Tailings piles are often acidic and laden with toxic metals.

Unvegetated tailing may be sources of dust and runoff.Unvegetated tailing may be sources of dust and runoff.


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Mining and the EnvironmentMining and the Environment

Sulfides react with OSulfides react with O22 to form sulfuric acid (Hto form sulfuric acid (H22SOSO44).).

This reacts with water forming acid mine drainage (AMD).This reacts with water forming acid mine drainage (AMD).

Water from spoil piles is acidified (pH


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USGS Mineral Resources ProgramUSGS Mineral Resources Program

http://minerals.usgs.gov/http://minerals.usgs.gov/

USGS Rare Earths Statistics and InformationUSGS Rare Earths Statistics and Information http://minerals.usgs.gov/minerals/pubs/commodity/rare_earths/http://minerals.usgs.gov/minerals/pubs/commodity/rare_earths/

WebElementsWebElements

http://www.webelements.com/http://www.webelements.com/

U.S. Department of the Interior Office of Surface MiningU.S. Department of the Interior Office of Surface Mining

http://www.osmre.gov/index.shtmhttp://www.osmre.gov/index.shtm

U.S. Environmental Protection Agency Acid Mine Drainage SiteU.S. Environmental Protection Agency Acid Mine Drainage Site

http://water.epa.gov/polwaste/nps/acid_mne.cfmhttp://water.epa.gov/polwaste/nps/acid_mne.cfm

Useful Web ResourcesUseful Web Resources

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