Rock Forming Minerals

 

Mafic

Biotite
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Biotite:  K (FE, Mg)3 AlSi3 O10 (F, OH)2, Potassium iron magnesium aluminum silicate hydroxide fluoride.

Hornblende
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Amphibole: Hornblende Ca2(Mg, Fe, Al)5(Al, Si)8O22(OH)2, Calcium Magnesium Iron Aluminum Silicate Hydroxide.

Augite
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Pyroxene: Augite (Ca, Na)(Mg, Fe, Al)(Al, Si)2 O6, Calcium Sodium Magnesium Iron Aluminum Silicate

Olivine
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Olivine: (Mg, Fe)2SiO4, Magnesium iron silicate.

Ca-plagioclase
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Ca-Plagioclase: CaAl2 Si2O8, Calcium aluminum silicate.

 

Felsic

Quartz

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Quartz: SiO2, Silicone oxide.  Typical quartz is
colorless and transparent, but there are also colored
varieties that are used as gemstones.  The picture at
the right shows a specimen of amethyst, a violet
colored variety that is quite popular.  Other varieties
are pink (rose quartz), yellow (citrine), and grayish
(smoky quartz).

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Muscovite
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Muscovite: KAl2(AlSi3O10)(F, OH)2, Potassium aluminum silicate hydroxide fluoride. 

Orthoclase
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Orthoclase: KAlSi3O8, Potassium Aluminum Silicate.

Albite
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Albite: NaAlSi3O8, Sodium aluminum silicate.