Tanzanite

Tanzanite bracelet

Description

Tanzanite stone

A pale-color transparent mineral that has been used as a Gemstone. Tanzanite is a variety of Zoisite composed of calcium aluminum silicate. Blue gem-quality stones were discovered in Tanzania in 1967. Tanzanite may be colorless, yellow-green, brown or bluish purple and refract flashes of blue, magenta and yellow. Most crystals are greenish gray and contain traces of Vanadium. These stones are commonly heat treated (600-700C) to produce a strong sapphire blue color gem.

Synonyms and Related Terms

zoisite; sorosilicate; Tansanit (Deut.); tanzanita (Esp.); tanzanite (Fr.)

IR spectrum of tanzanite from RRUFF

Raman spectrum of tanzanite from RRUFF

Physical and Chemical Properties

• Orthorhombic crystal system with prismatic crystals, massive to columnar
• Luster = vitreous to pearly
• Cleavage = perfect in one direction
• Fracture = uneven to conchoidal
• Streak = white to colorless
• Mohs Hardness = 6.0 - 6.5
• Density = 3.2-3.4 g/ml
• Refractive index = 1.691-1.700
• Birefringence = 0.008 - 0.013
• Pleochroism = Strong; dichroism or trichroism, usually blue, purplish red and greenish yellow
• Fluorescence = inert

Comparisons

Properties of Common Gemstones

Resources and Citations

• Gem Identification Lab Manual, Gemological Institute of America, 2016.
• Mineralogy Database: Zoisite
• R.F.Symmes, T.T.Harding, Paul Taylor, Rocks, Fossils and Gems, DK Publishing, Inc., New York City, 1997
• Encyclopedia Britannica, http://www.britannica.com Comment: "tanzanite" [Accessed 28 Sept. 2005].
• C.W.Chesterman, K.E.Lowe, Audubon Society Field Guide to North American Rocks and Minerals, Alfred A. Knopf, New York, 1979
• Wikipedia: Tanzanite (Accessed Sept. 28, 2005 and Dec 2022)
• Random House, Webster's Encyclopedic Unabridged Dictionary of the English Language, Grammercy Book, New York, 1997
• The American Heritage Dictionary or Encarta, via Microsoft Bookshelf 98, Microsoft Corp., 1998