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
Collins Discovery Encyclopedia, 1st edition © HarperCollins Publishers 2005
The following article is from The Great Soviet Encyclopedia (1979). It might be outdated or ideologically biased.

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.
The Great Soviet Encyclopedia, 3rd Edition (1970-1979). © 2010 The Gale Group, Inc. All rights reserved.

greenstone

[′grēn‚stōn]
(mineralogy)
(petrology)
Any altered basic igneous rock which is green due to the presence of chlorite, hornblende, or epidote.
McGraw-Hill Dictionary of Scientific & Technical Terms, 6E, Copyright © 2003 by The McGraw-Hill Companies, Inc.

greenstone

A basic igneous rock having a green color due to iron-bearing silicate minerals; quarried and fabricated for structural and decorative dimension stone.
McGraw-Hill Dictionary of Architecture and Construction. Copyright © 2003 by McGraw-Hill Companies, Inc.