Sphene (Titanite)

Common mineral of the silicates and germanates class.
The mineralogical name is "titanite".

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Sphen Titanit

Origin of name: first found 1795 in the graphite mines of Hauzenberg, Bavaria, the mineral was named by German chemist Martin Heinrich Klaproth because of it´s titanium content.

Synonyms and trade names: Sphene, from Greek σφήν sphén ("wedge"), because of the often wedge-shaped crystals

Can be confused with: e.g.Zircon, Spalerite, Scheelite. Because of the extremely high dispersion ("fire"), green titanite could be confused with demantoid garnet.

Localities: more than 4500 deposits on all continents including Antarctica.

Handling: due to it´s relatively low hardness, distinct cleavage and susceptibility to acids (fully soluble sulphuric acid!) bases and heat (unset before soldering!), titanite´s suitability as a gem stone is limited.

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Gemmological Properties of Sphene (Titanite)

Formula:
CaTi(SiO4)O
Crystal system:
monoclinic
Mohs hardness:
5 - 5.5
Specific gravity:
3.48 - 3.60
Refractive index:
1.84 - 2.11 biaxial (+)
Max. Birefringence:
0.100 - 0.160
Dispersion:
extreme
Pleochroism:
colourless, yellow to green, orange to red
Luminiscence:
weak brown in shortwave UV
Lustre:
adamantine to resinous
Cleavage:
distinct
Fracture:
conchoidal, brittle
Colour:
colourless, grey, yellow, green, brown, orange, red