Tourmaline natural crystal 7,2g Afghanistan

Except for color and transparency, the whole group of tourmalines has the same properties.
Physical properties: Hardness 7–7.5, brittle, density 2.9–3.2 g / cm³, fission imperfect according to {1011}, shell fracture, uneven.
Optical properties: Color: various, depending on the variety. There are crystals that are multicolored in the transverse or longitudinal direction. Glassy gloss, transparency: transparent, translucent, opaque (according to the variety), white scratch with a color shade according to the color of the variety.