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Tremolite
Current inventory:  0 gems
 

  
Tremolite was named by J.G.A. Höpfner for the Tremola valley (Val Tremola), Central St Gotthard Massif, Switzerland, where the type material supposedly came from, according to the dealer from whom he had acquired the specimens. See more name information below.

Discovered in 1790;   IMA status: Valid (pre-IMA; Grandfathered).

Chemistry

Chemical Formula:

Ca₂(Mg;Fe²⁺)₅Si₈O₂₂(OH)₂

Calcium Magnesium Iron Silicate Hydroxide

Molecular Weight:

812.37 gm

Composition: 

Classification

Mineral Classification:

Silicates

Strunz 8th Ed. ID:

8/F.10-10

Nickel-Strunz 10th Ed. ID:

9.DE.10

9 : SILICATES (Germanates)
D : Inosilicates
E : Inosilicates with 2-periodic double chains, Si₄O₁₁; Clinoamphiboles

Related to:

Amphibole Group. Calcic Clino-Amphibole Subgroup. Tremolite - Sadanagaite Series. Tremolite - Parvo-manganotremolite Series. Actinolite - Tremolite Series. Ferro-Actinolite - Tremolite Series.

Varieties:

Chrome-Tremolite, Hexagonite

Synonyms:

Abhazite, Abkhazite, Calamite, Grammatite, Peponite, Sebesite

Crystal Data

Crystallography:

Monoclinic - Prismatic

Crystal Habit:

Elongated, stout prismatic, or flattened bladed crystals, to 20 cm; also fibrous, granular or columnar aggregates.

Twinning:

Simple or multiple, common || {100}; rarely multiple || {001}

Physical Properties

Cleavage:

[110] Perfect; partings on  [010], [100]

Fracture:

Sub-Conchoidal

Tenacity:

Brittle

Moh's Hardness:

5.0 - 6.0

Density:

2.99 - 3.03 (g/cm³)

Luminescence:

Fluorescent, SW UV = yellow, LW UV = pink

Radioactivity:

Not Radioactive

Optical Properties

Color:

White, Brown, Gray, Colorless, light to dark Green, light Yellow, Pink to Violet; colorless in thin section

Transparency:

Transparent to Translucent, Opaque

Luster:

Vitreous, Silky

Refractive Index:

1.599 - 1.637  Biaxial ( - )

Birefringence:

0.0250 - 0.0260

Dispersion:

Weak; r < v

Pleochroism:

None

Occurances

Geological Setting:

From contact metamorphism of Ca-Mg siliceous sediments; in greenschist facies metamorphics derived from ultramafic or magnesium carbonate rocks.

Common Associations:

Calcian Garnet, Calcite, Cummingtonite, Diopside, Dolomite, Forsterite, Magnesio-cummingtonite, Riebeckite, Talc, Winchite, Wollastonite

Common Impurities:

Ti, Mn, Al, Na, K, F, Cl, H₂O

Type Locality:

Campolungo, Piumogna Valley, Leventina, Ticino (Tessin), Switzerland

Year Discovered:

1790

View mineral photos:

Tremolite Mineral Photos and Locations

More Information

Mindat.org
Webmineral.com

Tremolite is a relatively common mineral but rare as a faceted gem. Most mineral specimens are fibrous, granular or columnar aggregates and not suitable for faceting. The crystals that are transparent, clean and brightly colored are very rare. Tremolite is a member of the Calcic Clino-Amphibole Subgroup of the Amphibole Group of minerals that includes Actinolite, Ferro-edenite, Kaersutite, Pargasite, Richterite and Tremolite. The Amphibole Group is an extensive and complex group of minerals currently divided into several sub-groups. Gem quality Tremolite gets its vivid green coloring from the iron (Fe) content. A pale lilac to purplish color variety of Tremolite is called Hexagonite and is colored by manganese (Mn).

Tremolite was named by J.G.A. Höpfner for the Tremola valley (Val Tremola), Central St Gotthard Massif, Switzerland, where the type material supposedly came from, according to the dealer from whom he had acquired the specimens. Though, modern investigations of what is considered the type material, conserved at Geneva, revealed that the type locality is actually Campolungo. Val Tremola lying north of the isograde delineating the first appearance of tremolite.

The only notable sources of gem quality crystals of Tremolite are Harcourt, Haliburton County, Ontario, Canada; Outokumpu, Itä-Suomen Lääni, Finland; Umba Valley region, Kenya; Northern Areas, Astor District Astor, Pakistan. In the USA, from Pierrepont, Gouverneur, Edwards, and Macomb, St. Lawrence County, New York; at Franklin, Sussex County, New Jersey; and Lee, Berkshire County, Massachusetts.
 

  
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