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Tremolite
Current inventory:  0 gems
 

Tremolite

  
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:

Calcium

9.87 %

Ca

13.81 %

CaO

 

Magnesium

14.96 %

Mg

24.81 %

MgO

 

Silicon

27.66 %

Si

59.17 %

SiO2

 

Hydrogen

0.25 %

H

2.22 %

H2O

 

Oxygen

47.27 %

O

 

 

 

 

100.00 %

 

100.00 %

= TOTAL OXIDE

 

 

Classification

   

   

Mineral Classification:

SILICATES (Germanates) 

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, Si
4O11; Clinoamphiboles

Related to:

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

Members of Supergroup:

Amphibole Supergroup: Lithium Amphibole Subgroup, Lithium - (Magnesium - Iron - Manganese) Amphibole Subgroup, Lithium-Calcium Amphibole Subgroup, Magnesium - iron - manganese Amphibole Subgroup, Sodium Amphibole Subgroup, Sodium - (Magnesium - Iron - Manganese) Amphibole Subgroup, Sodium-Calcium Amphibole Subgroup

Varieties:

Chrome-Tremolite, Hexagonite

Synonyms:

Abhazite, Abkhazite, Calamite, Grammatite, Peponite, Raphilite, Säulenspath, Sebesite, Sternspath

 

 

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:

Perfect on [110]; 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

Health Warning:

Asbestiform varieties of Tremolite can cause lung disease when inhaled, as with other species of asbestos minerals.

 

 

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). A green chromium (Cr) rich variety called Chrome Tremolite is found mainly in the Merelani Hills of Tanzania.

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; Merelani Hills (Mererani), Lelatema Mts, Simanjiro District, Manyara Region, Tanzania. 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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