Amphibolite(redirected from Amphibolite (1911 Encyclopaedia Britannica))
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a schistose metamorphic rock composed chiefly of alumina-bearing amphibole (hornblende) and plagiociase; sometimes contains granite. Amphibolite is formed from various matrices subjected to profound metamorphism sometimes accompanied by metasomatism and the introduction of silica, magnesium, and iron. Some black varieties of amphibolite are used as industrial gems and ashlars.