This sample contains large crystals of black titanite, orange feldspar, and rusty red quartz. Titanite, also called sphene, has composition CaTiSiO5. It is a ve — Photo: Shannon Heinle · CC0
Titanite
Also known as: Sphene.
Calcium titanium silicate — 'sphene' — wedge-shaped crystals with fire exceeding diamond's.
Intro adapted from Wikipedia (CC BY-SA).
Titanite is an IMA-recognized mineral species in the silicate class, with the chemical formula CaTi(SiO₄)O.
It crystallizes in the monoclinic crystal system (space group C2/c). It is a member of the Titanite structural group.
Key properties: Mohs hardness 5–5.5; specific gravity 3.48–3.6; typically brown or green or yellow or black or pink; White streak; Adamantine to resinous luster; refractive index 1.96; optically biaxial.
IMA symbol Ttn, IMA status: approved, named in 1795.
A common accessory mineral in intermediate and felsic plutonic rocks, pegmatites, and alpine veins. In gneisses, schists, and some skarns; rarely detrital.
It is found associated with Albite, chlorite, epidote, apatite, allanite, monazite, magnetite, ilmenite, nepheline, biotite, diopside, calcite.
The name refers to TITANium in its composition.
Collections: Collector Favorites, Gemstones.