Tremolite

Big Photo

Hexagonite
Fowler, St. Lawrence Co., New York, USA
2.07 carats
© Rarestone.com

Tremolite is named after its discovery locality, in Val Tremola, near St. Gotthard, Switzerland.

Tremolite occurs as grey, green or lavender to pink stout elongated crystals, which form fibrous, granular or columnar aggregates. They are known as fine needle-like inclusions in quartz or emerald. The needles produce a distinct cat's eye effect in cabochons cut from compact green Tremolite from Ontario, Canada.

Tremolite Gemstones by Colour

This table shows the variety of hues this gemstone can be found in. Click on a photo for more information.
 
General Information
Varieties/Types:
Chrome-Tremolite - A chromian Tremolite.
Hexagonite - A transparent lilac-pink variety of Tremolite.
Chemical Formula
Ca
 
2
Mg
 
5
Si
 
8
O
 
22
(OH)
 
2
Ulrich Henn and Claudio C. Milisenda, Gemmological Tables (2004)
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Photos of natural/un-cut material from mindat.org
Physical Properties of Tremolite
Mohs Hardness5 to 6
Herve Nicolas Lazzarelli, Blue Chart Gem Identification (2010)
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Specific Gravity2.95 to 3.07
Walter Schumann, Gemstones of the world (2001)
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Cleavage QualityDistinct
Ulrich Henn and Claudio C. Milisenda, Gemmological Tables (2004)
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FractureUneven
Arthur Thomas, Gemstones (2009)
Optical Properties of Tremolite
Refractive Index1.599 to 1.637
Herve Nicolas Lazzarelli, Blue Chart Gem Identification (2010)
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Optical CharacterBiaxial/-
Herve Nicolas Lazzarelli, Blue Chart Gem Identification (2010)
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Birefringence0.023 to 0.028
Herve Nicolas Lazzarelli, Blue Chart Gem Identification (2010)
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PleochroismNil
Arthur Thomas, Gemstones (2009)
DispersionNil
Arthur Thomas, Gemstones (2009)
ChatoyancyYes
Ulrich Henn and Claudio C. Milisenda, Gemmological Tables (2004)
Colour
Colour (General)Grey-brown, green, colourless, white, pink.
Walter Schumann, Gemstones of the world (2001)
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Causes of ColourPink (hexagonite), Mn3+
W. William Hanneman, Pragmatic Spectroscopy For Gemologists (2011)
TransparencyTransparent,Translucent
Ulrich Henn and Claudio C. Milisenda, Gemmological Tables (2004)
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LustreVitreous,Silky
Walter Schumann, Gemstones of the world (2001)
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Fluorescence & other light emissions
Fluorescence (General)Occasionally orange
Ulrich Henn and Claudio C. Milisenda, Gemmological Tables (2004)
Crystallography of Tremolite
Crystal SystemMonoclinic
Herve Nicolas Lazzarelli, Blue Chart Gem Identification (2010)
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HabitFibrous, granular or columnar aggregates
Michael O’Donoghue, Gems, Sixth Edition (2006)
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Geological Environment
Where found:Tremolite is formed by contact metamorphism of Ca–Mg siliceous
sediments and in metamorphics derived from ultramafic or magnesium carbonate rocks.
Michael O’Donoghue, Gems, Sixth Edition (2006)
Further Information
Mineral information:Tremolite information at mindat.org
Significant Gem Localities
Kenya
 
  • Taita-Taveta County
Natural History Museum Vienna collection
USA
 
  • New York
    • St. Lawrence Co.
[var: Hexagonite]
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