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.

Cause of Color :
  • Yellowish green: Rare earth elements
  • Intense green: Chromium
Chemical Composition :

Silicate of Calcium and Titanium – CaTiSiO5

Crystal System / Forms :

Monoclinic System / Flattened, prismatic also massive compact.

Cuts & Uses :

Facetted cuts, cabochons, beads, etc.

Dispersion : 0.051
Hardness : 5.5
Lustre : Adamantine to Resinous
Magnification :

Crystals, fingerprints (spectral color in fingerprints due to dispersion), doubling

Optic Character :

Anisotropic, D.R., Biaxial positive

Pleochroism : Strong: Pale yellow, brownish yellow and orangish brown / colorless, yellow and reddish yellow
Refractive Index / Birefringence :

1.900 – 2.034 / ± 0.134; Range: 1.880 – 2.193

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)

Sources :

Sri Lanka, India (Tamil Nadu), Pakistan, Brazil, Madagascar, Mexico.

Specific Tests :

Strong doubling and dispersion

Spectrum :

Sometimes exhibits a 580nm – 595nm (didymium)

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