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Titanite (Sphene)
Titanite crystals on amphibole (image width 2 mm)
(repeating unit)
Strunz classification9.AG.15
Crystal symmetryP21/a
Unit cella = 7.057 Å, b = 8.707 Å
c = 6.555 Å; β = 113.81°; Z = 4
ColourReddish brown, brown, gray, black, yellow, green, or red, colourless
Crystal habitFlattened wedge-shaped crystals, also massive
Crystal systemMonoclinic
TwinningContact and penetration on {100}, lamellar on {221}
CleavageDistinct on [110], parting on {221}
Mohs scale hardness5 to 5.5
LusterSubadamantine tending to slightly resinous
StreakReddish white
DiaphaneityTranslucent to transparent
Specific gravity3.48 to 3.60
Optical propertiesBiaxial (+); very high relief
Refractive indexnα = 1.843 – 1.950
nβ = 1.870 – 2.034
nγ = 1.943 – 2.110
Birefringenceδ = 0.100 – 0.160
PleochroismStrong: X = nearly colorless; Y = yellow to green; Z = red to yellow-orange
2V angle17 to 40° (measured)
Dispersionr > v strong
Other characteristics Radioactive – may be metamict
Titanite crystal model

Titanite, or sphene (from the Greek sphenos (σφηνώ), meaning wedge[4]), is a calcium titanium silicate mineral. Its chemical formula is CaTiSiO5. Iron and aluminium are sometimes found in it. Also sometimes found in it are rare earth metals including cerium and yttrium, and the actinide thorium.[5]

References[change | change source]

  1. "Handbook of Mineralogy" (PDF).
  2. "Webmineral data".
  3. "Mindat".
  4. 4.0 4.1 Dana, James Dwight; Ford, William Ebenezer (1915). Dana's Manual of Mineralogy for the Student of Elementary Mineralogy, the Mining Engineer, the Geologist, the Prospector, the Collector, Etc (13 ed.). John Wiley & Sons, Inc. pp. 299–300. Retrieved 2009-07-06.
  5. Deer, W. A.; Howie, R. A.; Zussman, J. (1966). Introduction to the Rock-Forming Minerals. pp. 17–20. ISBN 0-582-44210-9.

Other websites[change | change source]