Tremolite Value, Price, and Jewelry Information

Optics

a =1.560-1.562; β= 1.613; γ=1-624-1.643

Biaxial (-), 2V= 81°.

Note: Tanzania, green crystals: 1.608-1.631, S.G. 3.02.

Occurrence

Tremolite occurs in contact and regionally metamorphosed dolomites, in magnesian limestones, and in ultrabasic rocks.

• California; Arizona; Utah; Colorado; Connecticut; South Dakota; Massachusetts.
• Italy; Switzerland; Austria.
• Fowler, New York: hexagonite, some cuttable; also at Edwards and Balmat, New York.
• Ontario and Quebec, Canada: gray, green and blue crystals; a chatoyant greenish variety found in Ontario cuts interesting catseye gems.
• Burma: green catseye gems.
• Lelatemu,Tanzania: green facetable crystals up to 25mm.
• Sierra Leone: Cr-rich tremolite, deep green with Cr spectrum displayed.

Comments

It is possible to misidentify tremolite, mistaking it for other amphiboles. Hexagonite is the rarest of the gem varieties of tremolite. If tremolite occurs in very tiny fibrous crystals, densely matted and interlocked, it is then known as nephrite (jade). Material containing more or less parallel fibers is somewhat chatoyant and yields weak catseyes. These are sometimes called catseye jades, but have been tested and are actually tremolite or (if more iron-rich) actinolite.

Name

From the Tremola Valley on the south side of St. Gotthard, Switzerland. Hexagonite was so named because it was thought to be a hexagonal mineral when first described.

Variety Names

 Hexagonite, purple Tremolite