Hornblende Kaolinite (clay) - City College of San Francisco · 5 Density separation during sand...

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Hornblende(Ca,Na)2-3(Fe,Mg,Al)5Si6(Si,Al)2O22(OH)2

Kaolinite (clay)Al2Si2O5(OH)4

Foliation ANIMATION

3

Why?How does texture change as grade increases?

Grains and crystals pack closer together under confining pressure

Density increases (volume shrinks)




Minerals align when under directed pressure

Foliation increases




Grain boundaries migrate, enlarging crystal size as pressure (any kind) placed on crystal boundaries.

Crystal size increases

Minerals align when under directed pressure

Foliation increases


Migmatitictexture

Very high

Gneissic texture

High

SchistosityMed to high

Phyllitictexture

Low to med

Rock or slatycleavage

Low

Description (+ picture)Foliation typeGrade

4

Microscopic, aligned mica minerals. Planar cleavage. No visible minerals. Dense.


Low

Description (+ picture)FoliationGrade

Mostly microscopic, aligned mica minerals. Only a few visible, isolated minerals peeking out of satiny background. Foliation is undulating.

Phyllitictexture

Low to med



Low


Mostly visible biotite minerals – all aligned, giving rock a scaly look, like a fish. Foliation is undulating and fine. Some large porphyroblasts may peek out.

SchistosityMed to high

Mostly microscopic, aligned mica minerals. Only a few visible, isolated minerals peeking out of satiny background. Foliation is undulating.

Phyllitictexture

Low to med



Low


5

Density separation during sand deposition (from hour glass)

All visible, interlocking crystals, separated into alternating dark- and light-colored layers.

Gneissic texture

High

Description (+ picture)Foliation type

Grade

6

Gneissic texture where ½ melted, and the high temperatures caused folding of the layers.

Migmatitictexture

Very high

All visible, interlocking crystals, separated into alternating dark- and light-colored layers.

Gneissic texture

High

Description (+ picture)Foliation type

Grade

---------------Pyroxene--------------------------------Hornblende-----------------

----------------------------Garnet-----------------------------------------------------------------------------Biotite------------------------------

-------------------------------Muscovite-----------------------------------------------------------------------------------------Calcite-------------------------------------------------------------------------------------------------------------------------Feldspar----------------------------------------------------------------------------------------------------------------------Quartz-----------------------------------------------------------

Low Medium HighGeneral mineral grade stability

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Core Mountain Garnet – from the Adirondack Mountains, NY – Museum of Natural History, NY. Garnet-bearing amphibolite – shows how metamorphism changes texture. Originally this rock was a GABBRO with olivine, pyroxene, and plagioclase. Under high T and P, water seeped into rock and reacted with original minerals to form hornblende and garnet. Water allowed for the large crystal size.

Chemically active fluids

TPMetamorphic setting

High – from magma and from heated surface waters

High: increasing toward magma

LowContact metamorphism (C)

Chemically active fluidsTPMetamorphic setting

Low – liberated from hydrous minerals and small amounts in cracks/pores

High: steadily increasing with depth


Regional metamorphism: Deep burial (B)






Low to medium: increasing with depth

High: increasing with depth

Regional metamorphism: Converging continents (R)









High – from hydrous minerals in hydrothermally altered ocean crust and water trapped in pores/cracks

Low: slowly increasing with depth

HighSubduction zone metamorphism (S)













High – from magmas and from circulating seawater

High because occurs at the Moho.

LowHydrothermal (H) circulation at spreading centers

High – from hydrous minerals in hydrothermally altered ocean crust and water trapped in pores/cracks

Low: slowly increasing with depth

HighSubduction zone metamorphism (S)













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Sills – Glacier National Park

Basalt Sill, Glacier National Park, Montana

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Eroding Metamorphic RocksANIMATION

Review Display Samples

Review Metamorphic Rock Chart

Metamorphic Rocks Activity

There are some duplicate names in the boxes.

Metamorphic Rocks in North America Formulas You Need To Know

CaCO3

Mineral:

Sedimentary rock:

Metamorphic rock:

SiO2

Mineral:

Sedimentary rock:

Metamorphic rock:

CaCO3Mineral: Calcite

Sedimentary rock:

Metamorphic rock:

SiO2Mineral: Quartz

Sedimentary rock:

Metamorphic rock:


Sedimentary rock:Chalk, Limestone

(including coquina, calcarenite)

Metamorphic rock:

SiO2Mineral: Quartz

Sedimentary rock:Quartz Sandstone,

Chert, Diatomite

Metamorphic rock:


Sedimentary rock:Chalk, Limestone

(including coquina, calcarenite)

Metamorphic rock:Marble

SiO2Mineral: Quartz

Sedimentary rock:Quartz Sandstone,

Chert, Diatomite

Metamorphic rock:Quartzite

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GRADE:LowLow - MedMed - HighHighVery High

Limestone(CaCO3)

Chert (SiO2)BasaltGraniteShaleParent rock

B, R, SB, R, SSB, R, SB, R, SMetamorphic settings


Mantle rock (Peridotite)

BasaltShaleMixture of minerals

Limestone(CaCO3)

Chert(SiO2)

Parent rock

HCCCCCMetamorphic settings

SlatePhylliteSchistGneissMigmatite


Limestone(CaCO3)



GneissMigmatite



Limestone(CaCO3)



Greenstone

BlueschistEclogiteGneiss

Migmatite



Limestone(CaCO3)



Quartzite (crystals grow larger)

Greenstone


Migmatite



Limestone(CaCO3)



Marble (crystals grow larger)


Greenstone


Migmatite



Limestone(CaCO3)







Limestone(CaCO3)

Chert(SiO2)

Parent rock







Limestone(CaCO3)

Chert(SiO2)

Parent rock


Skarn(crystals grow larger; form new minerals)






Limestone(CaCO3)

Chert(SiO2)

Parent rock


HornfelsHornfelsSkarn(crystals grow larger; form new minerals)






Limestone(CaCO3)

Chert(SiO2)

Parent rock


SerpentiniteHornfelsHornfelsSkarn(crystals grow larger; form new minerals)






Limestone(CaCO3)

Chert(SiO2)

Parent rock


Serpentinite – Mt Diablo

Soils derived from serpentine are toxic to many plants, because of high levels of nickel, chromium, and cobalt; growth of many plants is also inhibited by low levels of potassiumand phosphorusand a low ratio of calcium/magnesium.

We have now completed this week’s question sheet.

On your own, review each question again. I recommend that you write out your answers

(synthesize your thoughts and notes and put the answers into your own words).

If something doesn’t make sense or to just get some feedback, come see the tutors or me during my office

hours.

Remember: The exam will contain ANY question from ANY question sheet for this section.

ROCK/MINERAL REVIEW

Hornblende Kaolinite (clay) - City College of San Francisco · 5 Density separation during sand...

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