Clay Mineralogy. Clay is a particle SIZE Predominant make-up is SECONDARY minerals.
-
Upload
june-chandler -
Category
Documents
-
view
214 -
download
1
Transcript of Clay Mineralogy. Clay is a particle SIZE Predominant make-up is SECONDARY minerals.
![Page 1: Clay Mineralogy. Clay is a particle SIZE Predominant make-up is SECONDARY minerals.](https://reader030.fdocuments.us/reader030/viewer/2022032703/56649d1a5503460f949ef4cd/html5/thumbnails/1.jpg)
Clay Mineralogy
![Page 2: Clay Mineralogy. Clay is a particle SIZE Predominant make-up is SECONDARY minerals.](https://reader030.fdocuments.us/reader030/viewer/2022032703/56649d1a5503460f949ef4cd/html5/thumbnails/2.jpg)
• Clay is a particle SIZE
• Predominant make-up is SECONDARY minerals
![Page 3: Clay Mineralogy. Clay is a particle SIZE Predominant make-up is SECONDARY minerals.](https://reader030.fdocuments.us/reader030/viewer/2022032703/56649d1a5503460f949ef4cd/html5/thumbnails/3.jpg)
Minerals can be crystalline or amorphous.
Example: SiO2
crystalline QUARTZ (SiO2) : resistant to weathering
Amorphous silica (SiO2) : 10x more soluble
![Page 4: Clay Mineralogy. Clay is a particle SIZE Predominant make-up is SECONDARY minerals.](https://reader030.fdocuments.us/reader030/viewer/2022032703/56649d1a5503460f949ef4cd/html5/thumbnails/4.jpg)
1. Silicate Clays (crystalline)
2. Sesquioxide/oxidic clays
3. Amorphous clays (non-crystalline)
![Page 5: Clay Mineralogy. Clay is a particle SIZE Predominant make-up is SECONDARY minerals.](https://reader030.fdocuments.us/reader030/viewer/2022032703/56649d1a5503460f949ef4cd/html5/thumbnails/5.jpg)
1. Silicate Clays (aluminosilicates)
Micelle: particle of silicate clay
Composed of tetrahedral and octahedral “sandwiches”
Tetrahedron: central cation (Si+4, Al+3) surrounded by 4 oxygens
Octahedron: central cation (Al+3,Fe+2, Mg+2) surrounded by 6 oxygens (or hydroxyls)
![Page 6: Clay Mineralogy. Clay is a particle SIZE Predominant make-up is SECONDARY minerals.](https://reader030.fdocuments.us/reader030/viewer/2022032703/56649d1a5503460f949ef4cd/html5/thumbnails/6.jpg)
tetrahedron1.Silicate Clays
![Page 7: Clay Mineralogy. Clay is a particle SIZE Predominant make-up is SECONDARY minerals.](https://reader030.fdocuments.us/reader030/viewer/2022032703/56649d1a5503460f949ef4cd/html5/thumbnails/7.jpg)
1.Silicate Clays
![Page 8: Clay Mineralogy. Clay is a particle SIZE Predominant make-up is SECONDARY minerals.](https://reader030.fdocuments.us/reader030/viewer/2022032703/56649d1a5503460f949ef4cd/html5/thumbnails/8.jpg)
octahedron1.Silicate Clays
![Page 9: Clay Mineralogy. Clay is a particle SIZE Predominant make-up is SECONDARY minerals.](https://reader030.fdocuments.us/reader030/viewer/2022032703/56649d1a5503460f949ef4cd/html5/thumbnails/9.jpg)
1.Silicate Clays
![Page 10: Clay Mineralogy. Clay is a particle SIZE Predominant make-up is SECONDARY minerals.](https://reader030.fdocuments.us/reader030/viewer/2022032703/56649d1a5503460f949ef4cd/html5/thumbnails/10.jpg)
Tetrahedral sheets
Connected tetrahedra, sharing oxygens
1.Silicate Clays
![Page 11: Clay Mineralogy. Clay is a particle SIZE Predominant make-up is SECONDARY minerals.](https://reader030.fdocuments.us/reader030/viewer/2022032703/56649d1a5503460f949ef4cd/html5/thumbnails/11.jpg)
Octahedral sheets
Connected octahedra, sharing oxygens or hydroxyls
1.Silicate Clays
![Page 12: Clay Mineralogy. Clay is a particle SIZE Predominant make-up is SECONDARY minerals.](https://reader030.fdocuments.us/reader030/viewer/2022032703/56649d1a5503460f949ef4cd/html5/thumbnails/12.jpg)
• 1000s of tetrahedra and octahedra connect in clay minerals to give: – Planes of Si, Al, Mg– Planes of Oxygen, hydroxyl groups
• Sheets combine to form layers
• Layers are separated by interlayer space– Water, adsorbed cations
1.Silicate Clays
![Page 13: Clay Mineralogy. Clay is a particle SIZE Predominant make-up is SECONDARY minerals.](https://reader030.fdocuments.us/reader030/viewer/2022032703/56649d1a5503460f949ef4cd/html5/thumbnails/13.jpg)
1.Silicate Clays
![Page 14: Clay Mineralogy. Clay is a particle SIZE Predominant make-up is SECONDARY minerals.](https://reader030.fdocuments.us/reader030/viewer/2022032703/56649d1a5503460f949ef4cd/html5/thumbnails/14.jpg)
Isomorphous substitution
Lower charge cations replace higher charge cations as central cation– E.g., Mg+2 replaces Al+3
• leaves net negative charge
1.Silicate Clays
![Page 15: Clay Mineralogy. Clay is a particle SIZE Predominant make-up is SECONDARY minerals.](https://reader030.fdocuments.us/reader030/viewer/2022032703/56649d1a5503460f949ef4cd/html5/thumbnails/15.jpg)
1.Silicate Clays
![Page 16: Clay Mineralogy. Clay is a particle SIZE Predominant make-up is SECONDARY minerals.](https://reader030.fdocuments.us/reader030/viewer/2022032703/56649d1a5503460f949ef4cd/html5/thumbnails/16.jpg)
Different types of silicate clays are composed of sandwiches (combinations) of layers with various substances in their interlayer space.
2:1 two tetrahedral sheets to one octahedral sheet
1:1 one tetrahedron sheet to one octahedral sheet
1.Silicate Clays
![Page 17: Clay Mineralogy. Clay is a particle SIZE Predominant make-up is SECONDARY minerals.](https://reader030.fdocuments.us/reader030/viewer/2022032703/56649d1a5503460f949ef4cd/html5/thumbnails/17.jpg)
a. Kaolinite
1:1Hydrogen bonds in interlayer space
strong
NonexpandableLow CECParticles can grow very large (0.2 – 2
µm)Effective surface area = 10 – 30 m2/g
External surface only
1.Silicate Clays
![Page 18: Clay Mineralogy. Clay is a particle SIZE Predominant make-up is SECONDARY minerals.](https://reader030.fdocuments.us/reader030/viewer/2022032703/56649d1a5503460f949ef4cd/html5/thumbnails/18.jpg)
1.Silicate Clays
kaolinite
![Page 19: Clay Mineralogy. Clay is a particle SIZE Predominant make-up is SECONDARY minerals.](https://reader030.fdocuments.us/reader030/viewer/2022032703/56649d1a5503460f949ef4cd/html5/thumbnails/19.jpg)
1.Silicate Clays
kaolinite
![Page 20: Clay Mineralogy. Clay is a particle SIZE Predominant make-up is SECONDARY minerals.](https://reader030.fdocuments.us/reader030/viewer/2022032703/56649d1a5503460f949ef4cd/html5/thumbnails/20.jpg)
Kaolinite
good road basegood foundationgood for pottery; China clay
(porcelain)easy to cultivate, but need
manure or fertilizerDominant clay mineral in highly
weathered soils
1.Silicate Clays
![Page 21: Clay Mineralogy. Clay is a particle SIZE Predominant make-up is SECONDARY minerals.](https://reader030.fdocuments.us/reader030/viewer/2022032703/56649d1a5503460f949ef4cd/html5/thumbnails/21.jpg)
Kaolin mine, Bulgaria
![Page 22: Clay Mineralogy. Clay is a particle SIZE Predominant make-up is SECONDARY minerals.](https://reader030.fdocuments.us/reader030/viewer/2022032703/56649d1a5503460f949ef4cd/html5/thumbnails/22.jpg)
Kaolinite mine, MN(MN River Valley)
![Page 24: Clay Mineralogy. Clay is a particle SIZE Predominant make-up is SECONDARY minerals.](https://reader030.fdocuments.us/reader030/viewer/2022032703/56649d1a5503460f949ef4cd/html5/thumbnails/24.jpg)
kaolinite1.Silicate Clays
![Page 25: Clay Mineralogy. Clay is a particle SIZE Predominant make-up is SECONDARY minerals.](https://reader030.fdocuments.us/reader030/viewer/2022032703/56649d1a5503460f949ef4cd/html5/thumbnails/25.jpg)
![Page 26: Clay Mineralogy. Clay is a particle SIZE Predominant make-up is SECONDARY minerals.](https://reader030.fdocuments.us/reader030/viewer/2022032703/56649d1a5503460f949ef4cd/html5/thumbnails/26.jpg)
b. Smectite
2:1Weathering productAlways negative due to isomorphous
substitutionLayers weakly held together by weak O-O
bonds or cation-O bondsCations adsorbed in interlayer spaceExpandableHigh CEC
1.Silicate Clays
![Page 27: Clay Mineralogy. Clay is a particle SIZE Predominant make-up is SECONDARY minerals.](https://reader030.fdocuments.us/reader030/viewer/2022032703/56649d1a5503460f949ef4cd/html5/thumbnails/27.jpg)
1.Silicate Clays
![Page 28: Clay Mineralogy. Clay is a particle SIZE Predominant make-up is SECONDARY minerals.](https://reader030.fdocuments.us/reader030/viewer/2022032703/56649d1a5503460f949ef4cd/html5/thumbnails/28.jpg)
1.Silicate Clays
![Page 29: Clay Mineralogy. Clay is a particle SIZE Predominant make-up is SECONDARY minerals.](https://reader030.fdocuments.us/reader030/viewer/2022032703/56649d1a5503460f949ef4cd/html5/thumbnails/29.jpg)
smectite Interlayer cations hold layers together
In dry soils, bonding force is strong and hard clods form; deep cracks
In wet soils, water is drawn into interlayer space and clay swells.
MontmorilloniteVertisolsDominant clay mineral of most MN soils
1.Silicate Clays
![Page 30: Clay Mineralogy. Clay is a particle SIZE Predominant make-up is SECONDARY minerals.](https://reader030.fdocuments.us/reader030/viewer/2022032703/56649d1a5503460f949ef4cd/html5/thumbnails/30.jpg)
smectite
High effective surface area = 650 – 800 m2/g Internal surface area >> external
Particles small
Most expandable of all clays
1.Silicate Clays
![Page 31: Clay Mineralogy. Clay is a particle SIZE Predominant make-up is SECONDARY minerals.](https://reader030.fdocuments.us/reader030/viewer/2022032703/56649d1a5503460f949ef4cd/html5/thumbnails/31.jpg)
![Page 33: Clay Mineralogy. Clay is a particle SIZE Predominant make-up is SECONDARY minerals.](https://reader030.fdocuments.us/reader030/viewer/2022032703/56649d1a5503460f949ef4cd/html5/thumbnails/33.jpg)
c. Fine-grained micas
2:1As mica crystallizes from magma:
Isomorphous substitution of Al+3 for Si+4 in tetrahedra high net negative charge
K+ ions in interlayer spaceStrongly binds layers
Non-expandable IlliteSurface area 70 -175 m2/g
1.Silicate Clays
![Page 35: Clay Mineralogy. Clay is a particle SIZE Predominant make-up is SECONDARY minerals.](https://reader030.fdocuments.us/reader030/viewer/2022032703/56649d1a5503460f949ef4cd/html5/thumbnails/35.jpg)
d. Vermiculite
2:1Forms from alteration of mica
Weathering removes some K+ ionsReplaced by hydrated cations in
interlayer spaceWater molecules and cations bridge
layers, so not as expandable as smectites
1.Silicate Clays
![Page 36: Clay Mineralogy. Clay is a particle SIZE Predominant make-up is SECONDARY minerals.](https://reader030.fdocuments.us/reader030/viewer/2022032703/56649d1a5503460f949ef4cd/html5/thumbnails/36.jpg)
Still have very high net negative charge
High CEC (highest of all clays)ExpandableOctahedral ions are Al, Mg, FeSurface area 600 – 800 m2/g
Internal >> external
1.Silicate Clays
![Page 37: Clay Mineralogy. Clay is a particle SIZE Predominant make-up is SECONDARY minerals.](https://reader030.fdocuments.us/reader030/viewer/2022032703/56649d1a5503460f949ef4cd/html5/thumbnails/37.jpg)
![Page 39: Clay Mineralogy. Clay is a particle SIZE Predominant make-up is SECONDARY minerals.](https://reader030.fdocuments.us/reader030/viewer/2022032703/56649d1a5503460f949ef4cd/html5/thumbnails/39.jpg)
e. Chlorite
2:1Central cations in octahedral sheets
is Fe or MgInterlayer space occupied by a
stable, positively charged octahedral sheet
Non-expandable70 -100 m2/g surface area
1.Silicate Clays
![Page 40: Clay Mineralogy. Clay is a particle SIZE Predominant make-up is SECONDARY minerals.](https://reader030.fdocuments.us/reader030/viewer/2022032703/56649d1a5503460f949ef4cd/html5/thumbnails/40.jpg)
![Page 42: Clay Mineralogy. Clay is a particle SIZE Predominant make-up is SECONDARY minerals.](https://reader030.fdocuments.us/reader030/viewer/2022032703/56649d1a5503460f949ef4cd/html5/thumbnails/42.jpg)
2. Sesquioxides / Oxidic Clays
Ultimate weathering productsUltisols and Oxisols
Very stable; persist indefinitelyYellow, red, brownFe or Al as central cationsLack negative charge
Don’t retain adsorbed cations
Non-expandableLow CEC
![Page 43: Clay Mineralogy. Clay is a particle SIZE Predominant make-up is SECONDARY minerals.](https://reader030.fdocuments.us/reader030/viewer/2022032703/56649d1a5503460f949ef4cd/html5/thumbnails/43.jpg)
Low fertility
Often are net positiveOften have enough Al or Mn to be
toxic to plantsHigh capacity to fix phosphorous so it
is not available to plantsHighly weathered so no more
nutrients to release in weathering
![Page 44: Clay Mineralogy. Clay is a particle SIZE Predominant make-up is SECONDARY minerals.](https://reader030.fdocuments.us/reader030/viewer/2022032703/56649d1a5503460f949ef4cd/html5/thumbnails/44.jpg)
Ultisol profile
![Page 45: Clay Mineralogy. Clay is a particle SIZE Predominant make-up is SECONDARY minerals.](https://reader030.fdocuments.us/reader030/viewer/2022032703/56649d1a5503460f949ef4cd/html5/thumbnails/45.jpg)
In heavily leached soils, sheets decompose into component Si tet. and Al oct.Al oct. often weather into gibbsite
Al(OH)3
![Page 46: Clay Mineralogy. Clay is a particle SIZE Predominant make-up is SECONDARY minerals.](https://reader030.fdocuments.us/reader030/viewer/2022032703/56649d1a5503460f949ef4cd/html5/thumbnails/46.jpg)
![Page 47: Clay Mineralogy. Clay is a particle SIZE Predominant make-up is SECONDARY minerals.](https://reader030.fdocuments.us/reader030/viewer/2022032703/56649d1a5503460f949ef4cd/html5/thumbnails/47.jpg)
3. Amorphous (non-crystalline)
silicatesAllophane and imogoliteCommon in volcanic ashHigh internal negative chargeHigh CECHigh water-holding capacitySurface area 100 – 1000 m2/g
![Page 48: Clay Mineralogy. Clay is a particle SIZE Predominant make-up is SECONDARY minerals.](https://reader030.fdocuments.us/reader030/viewer/2022032703/56649d1a5503460f949ef4cd/html5/thumbnails/48.jpg)
Plasticity and Stickiness plasticity stickiness
kaolinite Low Low
smectite High High
mica Low Low
vermiculite High High
chlorite Low Low
amorphous High Low
oxidic Low Low
![Page 49: Clay Mineralogy. Clay is a particle SIZE Predominant make-up is SECONDARY minerals.](https://reader030.fdocuments.us/reader030/viewer/2022032703/56649d1a5503460f949ef4cd/html5/thumbnails/49.jpg)
“Activity” of silicate clays
• refers to cation exchange capacity (CEC)– Ability to retain and supply nutrients– Fertility
• High activity clays:– Less weathered ; high effective surface area– smectite, vermiculite, mica (illite), chlorite
• Low activity clays:– More weathered; less effective surface area– kaolinite
![Page 50: Clay Mineralogy. Clay is a particle SIZE Predominant make-up is SECONDARY minerals.](https://reader030.fdocuments.us/reader030/viewer/2022032703/56649d1a5503460f949ef4cd/html5/thumbnails/50.jpg)
Family description in taxonomy includes clay
activity
• Example:• “Fine-loamy, mixed, superactive,
frigid Typic Hapludalfs”
![Page 51: Clay Mineralogy. Clay is a particle SIZE Predominant make-up is SECONDARY minerals.](https://reader030.fdocuments.us/reader030/viewer/2022032703/56649d1a5503460f949ef4cd/html5/thumbnails/51.jpg)
What determines clay minerals in a given soil?
Usually a mixtureClimateParent materialDegree of weathering
![Page 52: Clay Mineralogy. Clay is a particle SIZE Predominant make-up is SECONDARY minerals.](https://reader030.fdocuments.us/reader030/viewer/2022032703/56649d1a5503460f949ef4cd/html5/thumbnails/52.jpg)
![Page 53: Clay Mineralogy. Clay is a particle SIZE Predominant make-up is SECONDARY minerals.](https://reader030.fdocuments.us/reader030/viewer/2022032703/56649d1a5503460f949ef4cd/html5/thumbnails/53.jpg)
Generalized relationships:
Ultisols Kaolinite, oxidic clays
Oxisols
Alfisols Mica, vermiculite, smectite
Mollisols
Vertisols
Andisols Amorphous