Sphene

Sphene, also referred to as titanite, is known for its strong fire (its dispersion is higher than that of diamond) and rich colors, but it is seldom used in jewellery as it is too brittle and soft. Nevertheless, transparent yellow, green or brown gem-quality material is cut for collectors. Sphene is strongly pleochroic (showing three different colours), and has high birefringence (seen as doubling of the back facets) and adamantine lustre.

Gem-quality sphene occurs in cavities in metamorphic rocks such as gneiss and schist, and also in granite. Main localities are Austria, Canada, Switzerland, Madagascar, Mexico and Brazil.

Sphene Properties

Chemical Composition: 
Silicate of Calcium and Titanium - CaTiSiO5
Colors / Varieties: 
  • Colorless, yellow, yellow-green, brown, grey
  • Chatoyant variety
Crystal System / Forms: 
Monoclinic System / Flattened, prismatic also massive compact.
Hardness: 
5.5
Specific Gravity: 
3.52 - 3.54
Cleavage / Fracture: 
Distinct 1 directional cleavage / Conchoidal to splintery fracture
Optic Character: 
Anisotropic, D.R., Biaxial positive
Lustre: 
Adamantine to Resinous
Refractive Index / Birefringence: 
1.900 - 2.034 / ± 0.134; Range: 1.880 - 2.193
Pleochroism: 
Strong: Pale yellow, brownish yellow and orangish brown / colorless, yellow and reddish yellow
Dispersion: 
0.051
Magnification: 
Crystals, fingerprints (spectral color in fingerprints due to dispersion), doubling
U.V. Fluorescence: 
Inert
Spectrum: 
Sometimes exhibits a 580nm - 595nm (didymium)
Cause of Color: 
  • Yellowish green: Rare earth elements
  • Intense green: Chromium
Specific Tests: 
Strong doubling and dispersion
Simulants (with separation tests): 
Natural Zircon (optic figure, dispersion, spectrum), Demantoid (optic character, inclusions), Synthetic Cubic Zirconia (optic character, lustre, S.G.), Synthetic Rutile (dispersion, S.G.), Peridot (R.I., dispersion, spectrum, inclusions), Chrysoberyl (R.I., spectrum, doubling, dispersion)
Geological Occurrence: 
Sphene occurs as an accessory mineral in igneous rocks and in metamorphic rocks such as schist and granite; often as fine crystals.
Sources: 
Sri Lanka, India (Tamil Nadu), Pakistan, Brazil, Madagascar, Mexico.
Cuts & Uses: 
Facetted cuts, cabochons, beads, etc.