Biotite
Biotite mainly occurs in metamorphic rocks, granite and other
rocks. The color of biotite is from black to brown or green,
with glass luster. The shape is plate and column. In recent
years, biotite has been widely used in stone paint and other
decorative coatings.
The single crystal of wancheng biotite is short columnar and
plate-shaped, with a hexagonal cross-section and scaly
aggregate. Brown or black. The color becomes darker with the
increase of iron content. Other optical and mechanical
properties are similar to those of muscovite, with a relative
density of 2.**3.3.
