Spinel in Biotite tower. Biotite, also called black mica, a silicate mineral in the common mica group. Spinel is the magnesium/aluminium member of the larger spinel group of minerals. Its name comes from the Latin word spinella, which means spine in reference to its pointed crystals. Spinel comes in many colors: Blue, Black, Red, Green, Pink, Yellow, Purple, White, Orange & Brown Weight 3.5oz Measurements in pics. Spinel in Biotite Tower/Point
