greenstone

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greenstone

1. any basic igneous rock that is dark green because of the presence of chlorite, actinolite, or epidote
2. a variety of jade used in New Zealand for ornaments and tools

Greenstone

 

the name given to igneous rocks that have undergone regional metamorphism at low temperatures and whose color is determined by the high content of green minerals (chlorite, amphibole) formed out of primary magmatic minerals and glass. Mainly volcanic and, less often intrusive rocks that are basic, intermediate, and sometimes acid (rhyolite) in composition and that are formed in folded regions are altered into greenstone. In regions where greenstone is wide-spread, such as the Urals and the state of Nevada in the USA, it serves as an indicator of pyrite deposits.

REFERENCES

Winkler, H. Genezis metamorficheskikh porod. Moscow, 1969. (Translated from German.)
Marakushev, A. A.Problemy mineral’nykhfatsii metamorficheskikh i metasomaticheskikh gornykh porod. Moscow, 1965.

greenstone

[′grēn‚stōn]
(mineralogy)
(petrology)
Any altered basic igneous rock which is green due to the presence of chlorite, hornblende, or epidote.

greenstone

A basic igneous rock having a green color due to iron-bearing silicate minerals; quarried and fabricated for structural and decorative dimension stone.
References in periodicals archive ?
IGR's contiguous claim block within the greenstone belt is midway between the Amapari and Santa Maria Mines.
The Bogoin belt comprises a main north to south striking limb some 35 km long (up to 5 km wide) and three northwest trending limbs between 15 and 20 km long for a total of 80 km of exposed greenstones.
At Bakala and Bogoin II we have the ability to undertake the first modern era exploration on previously under-explored Archaean greenstone belts.
The primary objective at Empire Creek is the discovery of gold-bearing massive sulphide deposits in Permian-Triassic age Greenstone.
This 2,900 hectare (7,250 acre) concession is underlain by Paramaka greenstones.