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Titanite  (Sphene)
Current inventory:  0 gems
 

Chemistry:   CaTiSiO₅  [Calcium Titanium Silicate]

Discovered in 1795;   IMA status: Valid (pre-IMA; Grandfathered).
The name Titanite refers to its high TITANium content (24%). The name Sphene is from the Greek word sphenos for wedge referring to its characteristic wedge-shaped crystals.

Classification

Mineral Classification:

Silicates

Strunz 8th Ed. ID:

8/B.12-10

Nickel-Strunz 10th Ed. ID:

9.AG.15

9 : SILICATES (Germanates)
A : Nesosilicates
G : Nesosilicates with additional anions; cations in > [6] +- [6] coordination

Related to:

Titanite Group. Titanite - Malayaite Series. The titanium analogue of Malayaite. Isostructural with Durangite and Tilasite.

Crystal Data

Crystallography:

Monoclinic - Prismatic

Crystal Habit:

Crystals wedge-shaped, flattened or prismatic by extension along [110], to 16 cm; compact, massive.

Twinning:

On [100], contact and penetration; less commonly lamellar on [221].

Physical Properties

Cleavage:

[110] Distinct, [100] Imperfect, [112] Imperfect; parting due to twinning on [221]

Fracture:

Sub-Conchoidal

Tenacity:

Brittle

Hardness (Mohs):

5.0 - 5.5

Density:

3.48 - 3.60 (g/cm³)

Luminescence:

None

Radioactivity:

Mild; GRapi = 3,805.77 (Gamma Ray American Petroleum Institute Units)

Other:

May be metamict.

Optical Properties

Color:

Colorless, Reddish Brown, Red, Yellow, Green, Gray, Black

Transparency:

Transparent to Translucent to Opaque

Luster:

Adamantine to Resinous

Refractive Index:

1.843 - 2.110  Biaxial ( + )

Birefringence:

0.1030 - 0.1600  (high)

Dispersion:

Extreme; r > v

Pleochroism:

Visible; Distinct when deeply colored; X = nearly colorless; Y = yellow to green; Z = red to yellow-orange.

Occurances

Geological Setting:

A common accessory mineral in intermediate and felsic plutonic rocks, pegmatites, and alpine veins. In gneisses, schists, and some skarns; rarely detrital.

Common Associations:

Albite, Allanite, Apatite, Biotite, Calcite, Chlorite, Diopside, Epidote, Ilmenite, Magnetite, Monazite, Nepheline

Common Impurities:

Fe, Y, Mn, Al, Ce, Sr, Na, Nb, Ta, Al, Mg, V, F, Zr, Sn

Type Locality:

Passau, Bavaria, Germany

Year Discovered:

1795

View mineral photos:

Titanite Mineral Photos and Locations

More Information

Mindat.org
Webmineral.com

Sphene (also known as Titanite) is a beautiful gem with high dispersion, high refractive index (greater than Diamond), high birefringence and intense red, green and yellow colors. Unfortunately, it also has low hardness and is brittle so not recommenced for jewelry. Sphene is typically slightly to moderately included and clean gems are particularly rare and beautiful. Sphene may be mildly radioactive as defined in 49 CFR 173.403 (greater than 70 Bq/gram) due to the presence of the Rare Earth Elements (REE) Cerium (Ce), Lanthanum (La), Neodymium (Nd), Praeseodymium (Pr) and Samarium (Sm). Sphene may also be metamict. This means that the original crystal structure has been broken down and turned amorphous due to radiation damage.

Notable occurances of gemmy crystals include Gilget and Badakhshan Provinces, Afghanistan; Pi~no Solo. From Campo do Boa, Capelinha, Minas Gerais, Brazil; Antsiranana and Tuléar Provinces, Madagascar; Skardu District, Baltistan, Northern Areas, Pakistan; and Subpolar Ural Mountains, Russia.
 

  
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