Titanite
Titanite , formerly known as sphene, belongs to the silicate group. It contains calcium, titanium, and silicon. Its chemical formula is CaTi( SiO4 )O.
Like obsidian, titanite has a vitreous luster and is translucent. Its fracture is also conchoidal. Titanite has tabular or cuneiform (wedge-shaped) crystals. The density of titanite is slightly less than 3.6 (1 for water) and its hardness varies around 5/10 on the Mohs scale (10 for diamond). The streak on porcelain is white. It is a fragile rock. The color of its translucent crystals is highly variable and represents the entire visible spectrum, due to the secondary minerals that compose it, such as iron, tin, or aluminum. The name titanite comes from the fact that it contains titanium.
