M695 - Biotite, Montana

Biotite is a black mica.  Basic patassium, magnesium, iron, aluminum silicate. Hardness 2-1/2 to 3.  Forms in thin layers or plates.  Very elastic.  Opaque to translucent. From the Rocky Boy Indian Reservation, Havre, Montana.

SPECIAL PRICE Small size  - $ 6.95 each