-
-
Tridymite
- SiO2
- Hi T
- xls, scales or in cavities in acidic vol. rx
- 870-1470 C
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Cristobalite
- SiO2
- Hi T
- xls, scales or in cavities in acidic vol. rx
- stable above 1470 C
-
Feldspars
- KAlSi3O8 <---ss---> NaAlSi3O8 <---ss---> CaAl2Si2O8
- Sanidine
- Orthoclase
- Microcline
- Albite ---to--- Anorthite
-
Sanidine
- KAlSi3O8
- Hi T
- in felsic volcanic rx
- in solid solution with Albite
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-
Microcline
- KAlSi3O8
- K rich
- slow cooling of orthoclase
- colorless
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Plagioclase
Albite and Anorthite solid solution
- Albite NaAlSi3O8
- Oligoclase
- Andesine Ca, Al --> Na, Si
- Labradorite
- Bytownite
- Anorthite CaAl2Si2O8
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Oligoclase
- 10 - 30% Anorthite Ca, Al
- Mostly Albite Na, Si
- often accompanies orthoclase
-
Andesine
- 30 - 50% Anorthite
- mod to half Ca, Al rich
-
Labradorite
- 50 - 70% Anorthite
- half to more than Ca, Al rich
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Bytownite
70 - 90% Anorthite
mostly Ca, Al rich
-
Anorthite
- CaAl2Si2O8
- all the Na, and some Si replaced
- complete transfer from Albite
- 90-100%
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Feldspathoids
- lacking Si & O
- Nephaline NaAlSiO4
- Leucite KAlSi2O6
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-
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Olivines
- X2SiO4
- Forsterite X = Mg
- Fayalite X = Fe
- solid solution
- nesosilicate - isolated silica tetrahedra
-
Forsterite
- Mg2SiO4
- For + qtz -> Enst (orthopyx.)
- Mg2SiO4 + SiO2 -> 2 MgSiO3
-
Fayalite
- Fe2SiO4
- Fe stabilizes the olivine + qtz pair
- and doesn't react like Fors
-
Orthopyroxene
- (Mg,Fe)SiO3
- Orthorhombic
- solid solution of Enstatite (Mg) and Ferrosilite (Fe)
- Hypersthene is the general name for the common mixture of the two minerals.
-
Hypersthene
- MgSiO3 <----ss----> FeSiO3
- mixture of Enstatite and Ferrosilite
- commonly confused with Hbl, but Hyp is harder
- opx
-
Enstatite
- MgSiO3
- Orthopyroxene
- ss with Ferrosilite
-
Ferrosilite
- FeSiO3
- othopyroxene
- ss with Enstatite
-
Clinopyroxenes
- ABSi2O6 or X2Si2O6
- Diopside
- Hedenbergite
- Augite
- Pigeonite
- Wollastonite [CaSiO3]
- (all monoclinic)
-
Pyroxene
- XY(Si,Al)2O6
- single chain inosilicate
-
-
-
Augite
- (Ca,Mg,Fe)2Si2O6
- two cleavages meeting near 90o
- cpx
-
-
-
Amphibole
- RSi8O22 (OH,F)2
- doublechain inosilicate
-
-
Actinolite
- Ca2(Mg,Fe)5Si8O22(OH,F)2
- Amph
-
Hornblende
- (Ca,Na)2-3(Mg,Fe,Al)5Si6(Al,Si)2O22(OH,F)2
- Amph
-
Mica
- Phylosilicate
- X2Y4–6Z8O20(OH,F)4
- Biotite
- Muscovite
-
Biotite
- K(Mg,Fe)3(AlSi3O10)(OH,F)2 (Mg,Fe)3 = Al2
- Mica
-
Muscovite
- KAl2(AlSi3O10)(OH,F)2
- Mica
-
Garnet
- X3Al2Si3O12
- Grossular
- Pyrope
- Almandine
- nesosilicate
-
-
-
-
Andalusite
- Al2SiO5
- Al Nesosilicate
- polymorph to Ky and Sill
-
Kyanite
- Al2SiO5
- Al Nesosilicate
- polymorph to And and Sill
-
Sillimanite
- Al2SiO5
- Al Nesosilicate
- polymorph to Ky and And
-
-
-
-
Apatite
- Ca5(PO4)3(OH,F,Cl)2
- Phosphate mineral
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