Anthophyllite is an amphibole mineral: (Mg, Fe)7Si8O22(OH)2, magnesium iron inosilicate hydroxide. Anthophyllite is polymorphic with cummingtonite. It is a mineral of metamorphic origin produced by the alteration of magnesium rich igneous rocks and impure dolomitic limestone. Thus it is found in gneisses, schists, and some marbles. Anthophyllite also occurs as a retrograde metamorphic mineral derived from ultramafic rocks along with serpentine. Some forms of anthophyllite are lamellar or fibrous and are used as asbestos.
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