Mineral Information and Data:

Tremolite
[]Ca2Mg5Si8O22(OH)2 [CNMNC approved formula]

Named in 1792 after the locality: Tremola Valley, St. Gotthard, Switzerland.

IMA status : Redefined IMA Approved; 1997 ()
CLASSIFICATION 
Dana
(8th edition) :
66.01.03a.01  
  (66) Inosilicate Double-Width Unbranched Chains, W=2
  (66.01) with P=2 amphibole configuration
  (66.01.03a) Group 2, the calcic amphiboles
  
Nickel-Strunz
(10th edition) :
09.DE.10
  (09) Silicates
  (09.D) Inosilicates* Structural terminology per Liebau (1985)
  (09.DE) with 2-periodic double chains, Si4O11; Clinoamphiboles
  
Crystal system: Monoclinic System
Point group (H-M): 2/m — prismatic
Unit cell: a = 9.84 Å, b = 18.02 Å, c = 5.27 Å, b = 105.0°
Crystal Habit: Elongated, stout prismatic, bladed crystals, fibrous, granular, columnar aggregates.
Twinning: Common on {100} simple or lamellar, rare on {001} lamellar
  
Color: White, gray, lavender to pink;
Diaphaneity: Transparent, Translucent
Luster: Vitreous, Silky
Hardness (Mohs): 5 - 6
Measured Density: 2.9 to 3.2 g/cm3
Cleavage: 2; {110} good, {100} parting
Tenacity: Brittle
Streak: White
  
Polymorphism and Series: Forms a series with actinolite and ferro-actinolite.
Geologic Setting: From contact metamorphism of Ca-Mg siliceous sediments; in greenschist facies metamorphics derived from ultramafic or magnesium carbonate rocks.
Mineral Association: Calcite, dolomite, calcian garnet, wollastonite, talc, diopside, forsterite, cummingtonite, magnesio-cummingtonite, riebeckite, winchite
  
Synonyms/varieties: Abkhazite, byssolite (fibrous variety), calamite, grammatite, hexagonite (Mn-rich variety), hoepfnerite, nephrite (compact variety), nordenskiöldite
Other Properties: Gemstone Extremely Rare.

 

Tremolite
Origin: Gouverneur, New York, U.S.A.
Sample size: 7.5 x 6 x 5 cm
Photo: Dan Weinrich

 

Tremolite
(zoom-in of above)

 

Tremolite
Origin: Fowler, St. Lawrence Co., New York, U.S.A.
Sample size: about 4 cm across
Photo and Owner: Milton Speckels

 

Tremolite
Tremolite, variety hexagonite
Origin: Fowler, St Lawrence Co., New York, U.S.A.
Sample size: 15 x 12 x 7 cm
Photo: Rob Lavinsky

 

Tremolite
(zoom-in of above)

 

Tremolite
Nephrite on lazurite
Origin: Sar-E-Sang, Kokcha Valley, Badakhshan, Afghanistan
Sample size: 6.5 x 5.5 x 4 cm
Photo: Rob Lavinsky

 

Tremolite
(zoom-in of above)

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