|Habit||Wedge shaped, massive|
|Optic nature||Biaxial +|
|Lustre||Resinous to sub-adamantine|
|Pleochroism||Distinct to strong|
Sphene is the older name of this mineral wich refers to its crystalshape. Titanite is the universial name amongst mineralogists today and refers to its content of titanium. Greenovite is the name given to red or pink sphene. Gemologists use the name sphene for gem material titanite.
Sphene is isostructural with tilasite, malayaite and fersmantite.
Wedge-shaped crystals that may show parting due to twinning. Less common massive or lamellar. Sphene is normally fine grained but occacionally forms large crystals.
Sphene may show some degree of metamictization.
Yellow, brown, green, reddish.
Color is caused by rare earth elements (didymium) for yellow stones and chromium for the intense green chrome sphene.
Transparent to opaque.
nα = 1.843 - 1.950, nβ = 1.870 - 2.034, nγ = 1.943 - 2.110 with a birefringence of 0.100 - 0.192.
Optical nature: biaxial positive.
A strong doubling of facets is seen in cut stones.
Due to its small to moderate 2V value (17-40°) a clear biaxial interference pattern may be seen (two melatopes visible in one image).
Moderate to strong trichroism.
Yellow to brown stones: colourless, greenish-yellow, reddish.
Sometimes a spectrum can be seen.
Mean absorption lines: 586, 582. Sphene may show (weak) rare earth spectra due to didymium.
None (probably due to iron content).
- Chrome sphene, intense green (color caused by chromium).
- Greenovite, a reddish variety owning its color to manganese (MnO) impurities.
Sphene is changed to red or orange through heating.
Sphene's relative low hardness makes it vulnerable to abbrasion.
Sphene is a common and widespread mineral in many igneous rocks and metamorphic rocks. Associated minerals are pyroxene, amphibole, feldspar and quartz.
Facet-grade sphene was found in Mulla Ghani Baba in Mohmand Agency, NW of Peshawar, Pakistan, in 2004. The color of this sphene is medium to dark brown, and a significant 'red flash' was notable in the faceted gems. In Badadkshan, Afghanistan, sphene was also found in 2004. The color of Afghan sphene is greenish yellow. While India also produces fine sphene, Madagascar remains the main source for facet-grade sphene. While brown stones from Madagascar can be large, the green stones are most prized by gem collectors and connoisseurs.
Myanmar, Sri Lanka, Brazil, Mexico, Russia and Austria
- Gems sixth edition (2006) - Michael O'Donoghue ISBN 0750658568
- Gemstones of the world, 3rd rev and exp edition (2006) - Walter Schuman ISBN 1402740166
- Mineralogy second edition (2002) - Dexter Perkins ISBN 0130620998
- Introduction to Optical Mineralogy (2004) - William D. Nesse ISBN 0195149106
- Gemmology 3rd edition (2005) - Peter G. Read ISBN 0750664495
- Gem Reference Guide (1995) - GIA ISBN 0873110293