Biotite specimens for sale

Biotite is a common sheet silicate mineral that forms monoclinic crystals and dark, vitreous to sub-metallic surfaces. It typically appears as thin, flexible sheets with a pleochroic range from brown to greenish-bold hues, and it often displays a rhombohedral cleavage that allows it to split into platy flakes. In rock formations, biotite occurs in igneous and metamorphic environments and can be found in masses or as individual crystals embedded in schists and granites. Collectors prize the glossy, dark flakes for their distinctive luster and the way they reflex infrared light, producing subtle color shifts in different lights.