amphibole group

noun

: a group of minerals (as anthophyllite, tremolite, actinolite, and hornblende) with essentially like crystal structures involving a silicate chain [OH(Si₄O₁₁)]n and generally containing three groups of metal ions, the large ions being sodium and calcium, the intermediate being chiefly bivalent iron, magnesium, and manganese, and the small ions chiefly silicon with some aluminum and rarely ferric iron, the general formula for the group being A₂B₅(Si, Al)₈O₂₂(OH) ₂

Word History

First Known Use

1828, in the meaning defined above

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