Roger Weller, geology instructor
email@example.com copyright 2010-R.Weller
Biotite is K(Mg,Fe)3AlSi3O10(OH)2
Biotite is also known as black mica. It can be peeled off of a large crystal in thin
layers but with more difficulty than peeling muscovite (white mica). Biotite
does not have economic value because it lacks the transparency and electrical
insulating properties found in muscovite.
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Just credit photo to R.Weller/Cochise College.