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Amphibole mineral, a magnesium and iron silicate that occurs in altered rocks, such as the crystalline schists of Kongsberg, Norway; southern Greenland; and Pennsylvania. Anthophyllite is commonly produced by regional metamorphism of ultrabasic rocks (see acid and basic rocks).
This entry comes from Encyclopædia Britannica Concise. For the full entry on anthophyllite, visit Britannica.com.