Tourmalines are a group of minerals belonging to the class of silicates, order of cyclosilicates. The name derives from the Sinhalese turmali which literally means mixed package or stone of various colors. The crystal belongs to the trigonal system, it is prismatic, very elongated, vertically streaked and sometimes with unequal development at the two ends of the vertical axis. Its color depends on the chemical composition and may not be uniform in the crystal. In black tourmaline the color is given by the presence of iron inside.
Dimensions
Black Tourmaline available in 2 Sizes:
Height (cm):
Small: about 3-4
Large: about 4.5
Depth (cm):
Small: about 2-3
Large: about 4
Width (cm):
Small: about 3-4
Large: about 6
Weight (g):
Small: 70-100
Large: 150-220
Property
Chemical Formula: -
Mohs scale: 7-7.5
Relative density: 2.9-3.2
Crystalline System: Trigonal