Tremolite
A variety of Minerals
What is Tremolite?
Tremolite is a member of the amphibole group of silicate minerals with composition: Ca2(Mg5.0-4.5Fe0.0-0.5)Si8O22(OH)2. Tremolite forms by metamorphism of sediments rich in dolomite and quartz. Tremolite forms a series with actinolite and ferro-actinolite. Pure magnesium tremolite is creamy white, but the color grades to dark green with increasing iron content. It has a hardness on Mohs scale of 5 to 6. Nephrite, one of the two minerals of the gemstone jade, is a green variety of tremolite. The fibrous form of tremolite is one of the six recognised types of asbestos. This material is toxic, and inhaling the fibers can lead to asbestosis, lung cancer and both pleural and peritoneal mesothelioma. Fibrous tremolite is sometimes found as a contaminant in vermiculite, chrysotile (itself a type of asbestos) and talc.
Optical Properties
- Refractive Index
- 1.599-1.637
- Birefringence
- 0.023-0.028
- Pleochroism
- None
- Optical Character
- Biaxial negative
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Tremolite Localities Map
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The Meaning
Tremolite is considered a secondary birthstone for the signs of Scorpio, Pisces, Gemini and Libra.
Key Characteristics
Formation of Tremolite
Tremolite is an indicator of metamorphic grade since at high temperatures it converts to diopside. Tremolite occurs as a result of contact metamorphism of calcium and magnesium rich siliceous sedimentary rocks and in greenschist facies metamorphic rocks derived from ultramafic or magnesium carbonate bearing rocks. Associated minerals include calcite, dolomite, grossular, wollastonite, talc, diopside, forsterite, cummingtonite, riebeckite and winchite. Tremolite was first described in 1789 for an occurrence in Campolungo, Piumogna Valley, Leventina, Ticino (Tessin), Switzerland.
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Quick Facts
Physical Properties
- Color
- White, brown, colourless, grey, light green, green, light yellow, pink-violet
- Hardness (Mohs)
- 5 - 6
- Density
- 2.964 g/cm³
- Streak
- White
Chemical Properties
- Chemical Formula
- ☐{Ca2}{Mg5}(Si8O22)(OH)2
- Elements
- Ca, H, Mg, O, Si
Also Known As
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