Mica

* The important species of the mica group are: muscovite, common or potash mica, pale brown or green, often silvery, including damourite (also called hydromica); biotite, iron-magnesia mica, dark brown, green, or black; lepidomelane, iron, mica, black; phlogopite, magnesia mica, colorless, yellow, brown; lepidolite, lithia mica, rose- red, lilac.

Mica (usually muscovite, also biotite) is an essential constituent of granite, gneiss, and mica slate; biotite is common in many eruptive rocks; phlogopite in crystalline limestone and serpentine.

Mica diorite (Min.), an eruptive rock allied to diorite but containing mica (biotite) instead of hornblende. -- Mica powder, a kind of dynamite containing fine scales of mica. -- Mica schist, Mica slate (Geol.), a schistose rock, consisting of mica and quartz with, usually, some feldspar.