Biotite
Biotite color is black, ark brown, sometimes with light red, light green or other colors. Titania's pale reddish-brown, rich in high-priced iron are green, Transparent to opaque. Glass gloss, black is a semi metallic luster. Hardness 2-3, specific gravity 3.02-3.12. The role of biotite heated solution can be altered to chlorite, muscovite and sericite and other minerals. Because biotite has the high iron content, poor insulation, much less than muscovite. Biotite flakes usually is used as filler of building materials. Black mica flake of larger particle size easily according to their shape, dark colors, and flexibility, with complete cleavage of mica, and after heating.
