Sodium-rich member of the amphibole group of silicate minerals
Riebeckite is a sodium-rich member of the amphibole group of silicate minerals, chemical formula Na2(Fe2+3Fe3+2)Si8O22(OH)2. It forms a solid solution series with magnesioriebeckite. It crystallizes in the monoclinic system, usually as long prismaticcrystals showing a diamond-shaped cross section, but also in fibrous, bladed, acicular, columnar, and radiating forms. Its Mohs hardness is 5.0–6.0, and its specific gravity is 3.0–3.4. Cleavage is perfect, two directions in the shape of a diamond; fracture is uneven, splintery. It is often translucent to nearly opaque.
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Riebeckite
Black riebeckite in an alkaline pegmatite from Lindinosa near Évisa, Corsica, France
Riebeckite was first described in 1888 for an occurrence on Socotra Island, Aden Governorate, Yemen, and named after German explorer Emil Riebeck (1853–1885).[3]
The riebeckite granite known as ailsite, found on the island of Ailsa Craig in western Scotland, is prized for its use in the manufacture of curling stones.
Riebeckite granite was used for the facing stones of the Canton Viaduct from Moyles Quarry (a.k.a. Canton Viaduct Quarry) now part of Borderland State Park in Massachusetts, US. The commonwealth's name is even taken from an Algonquian word for the Great Blue Hill, which got its color from this form of granite.
Crocidolite (fibrous riebeckite)
The fibrous forms of riebeckite are known as crocidolite and are one of the six recognised types of asbestos. Often referred to as blue asbestos, it is considered the most hazardous. The association between blue asbestos and mesothelioma was established by J. C. Wagner, C. A. Sleggs, and P. Marchand by 1960.[7]
Medicine, Institute of; Practices, Board on Population Health and Public Health; Effects, Committee on Asbestos: Selected Health (2006-09-23). Asbestos: Selected Cancers. National Academies Press. ISBN978-0-309-10169-1.
This article uses material from the Wikipedia article Crocidolite, and is written by contributors.
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