Tremolite is a member of the

amphibole Amphibole ( ) is a group of inosilicate minerals, forming prism or needlelike crystals, composed of double chain tetrahedra, linked at the vertices and generally containing ions of iron and/or magnesium in their structures. Its IMA symbol is ...

group of

silicate minerals Silicate minerals are rock-forming minerals made up of silicate groups. They are the largest and most important class of minerals and make up approximately 90 percent of Earth's crust. In mineralogy, the crystalline forms of silica (silicon dio ...

with composition Ca₂(Mg_5.0-4.5Fe²⁺_0.0-0.5)Si₈O₂₂(OH)₂. Tremolite forms by

metamorphism Metamorphism is the transformation of existing Rock (geology), rock (the protolith) to rock with a different mineral composition or Texture (geology), texture. Metamorphism takes place at temperatures in excess of , and often also at elevated ...

of sediments rich in dolomite and

quartz Quartz is a hard, crystalline mineral composed of silica (silicon dioxide). The Atom, atoms are linked in a continuous framework of SiO4 silicon–oxygen Tetrahedral molecular geometry, tetrahedra, with each oxygen being shared between two tet ...

, and occurs in two distinct forms, crystals and fibers. Tremolite forms a series with actinolite and ferro-actinolite. Pure

magnesium Magnesium is a chemical element; it has Symbol (chemistry), symbol Mg and atomic number 12. It is a shiny gray metal having a low density, low melting point and high chemical reactivity. Like the other alkaline earth metals (group 2 ...

tremolite is creamy white, but the color grades to dark green with increasing

iron Iron is a chemical element; it has symbol Fe () and atomic number 26. It is a metal that belongs to the first transition series and group 8 of the periodic table. It is, by mass, the most common element on Earth, forming much of Earth's o ...

content. It has a hardness on

Mohs scale The Mohs scale ( ) of mineral hardness is a qualitative ordinal scale, from 1 to 10, characterizing scratch resistance of minerals through the ability of harder material to scratch softer material. The scale was introduced in 1812 by the Ger ...

of 5 to 6. Nephrite, one of the two minerals known as the gemstone

jade Jade is an umbrella term for two different types of decorative rocks used for jewelry or Ornament (art), ornaments. Jade is often referred to by either of two different silicate mineral names: nephrite (a silicate of calcium and magnesium in t ...

, is a green crystalline variety of tremolite. The fibrous form of tremolite is one of the six recognised types of

asbestos Asbestos ( ) is a group of naturally occurring, Toxicity, toxic, carcinogenic and fibrous silicate minerals. There are six types, all of which are composed of long and thin fibrous Crystal habit, crystals, each fibre (particulate with length su ...

. This material is toxic, and inhaling the fibers can lead to

asbestosis Asbestosis is long-term inflammation and pulmonary fibrosis, scarring of the human lung, lungs due to asbestos fibers. Symptoms may include shortness of breath, cough, wheezing, and chest pain, chest tightness. Complications may include lung canc ...

lung cancer Lung cancer, also known as lung carcinoma, is a malignant tumor that begins in the lung. Lung cancer is caused by genetic damage to the DNA of cells in the airways, often caused by cigarette smoking or inhaling damaging chemicals. Damaged ...

and both

pleural The pleural cavity, or pleural space (or sometimes intrapleural space), is the potential space between the pulmonary pleurae, pleurae of the pleural sac that surrounds each lung. A small amount of serous fluid, serous pleural fluid is maintained ...

and peritoneal mesothelioma. Fibrous tremolite is sometimes found as a contaminant in vermiculite, chrysotile (itself a type of asbestos) and

talc Talc, or talcum, is a clay mineral composed of hydrated magnesium silicate, with the chemical formula . Talc in powdered form, often combined with corn starch, is used as baby powder. This mineral is used as a thickening agent and lubricant ...

Occurrence

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 rock Sedimentary rocks are types of rock (geology), rock formed by the cementation (geology), cementation of sediments—i.e. particles made of minerals (geological detritus) or organic matter (biological detritus)—that have been accumulated or de ...

s and in greenschist facies metamorphic rocks derived from

ultramafic Ultramafic rocks (also referred to as ultrabasic rocks, although the terms are not wholly equivalent) are igneous and meta-igneous rocks with a very low silica content (less than 45%), generally >18% MgO, high FeO, low potassium, and are usua ...

or magnesium carbonate bearing rocks. Associated minerals include

calcite Calcite is a Carbonate minerals, carbonate mineral and the most stable Polymorphism (materials science), polymorph of calcium carbonate (CaCO3). It is a very common mineral, particularly as a component of limestone. Calcite defines hardness 3 on ...

, dolomite, grossular,

wollastonite Wollastonite is a calcium Silicate minerals, inosilicate mineral (calcium, Casilicon, Sioxygen, O3) that may contain small amounts of iron, magnesium, and manganese substituting for calcium. It is usually white. It forms when impure limestone or D ...

, diopside,

forsterite Forsterite (Mg2SiO4; commonly abbreviated as Fo; also known as white olivine) is the magnesium-rich Endmember, end-member of the olivine solid solution series. It is Isomorphism (crystallography), isomorphous with the iron-rich end-member, fayalit ...

, cummingtonite, riebeckite and winchite. Tremolite was first described in 1789 for an occurrence in Campolungo, Piumogna Valley, Leventina,

Ticino Ticino ( ), sometimes Tessin (), officially the Republic and Canton of Ticino or less formally the Canton of Ticino, is one of the Canton of Switzerland, 26 cantons forming the Switzerland, Swiss Confederation. It is composed of eight districts ...

(Tessin),

Switzerland Switzerland, officially the Swiss Confederation, is a landlocked country located in west-central Europe. It is bordered by Italy to the south, France to the west, Germany to the north, and Austria and Liechtenstein to the east. Switzerland ...

Fibrous tremolite

One of the six recognized types of

, approximately 40,200 tons of tremolite asbestos is mined annually in India. It is otherwise found as a contaminant.

References

{{Reflist
Mineral may unlock secrets of Venus's ancient oceans
New Scientist, ''10 October 2007'' Calcium minerals Magnesium minerals Asbestos Amphibole group Monoclinic minerals Minerals in space group 12 Luminescent minerals

Occurrence

Fibrous tremolite

See also

References