Nomenclature of the amphibole supergroup

A new classification and nomenclature scheme for the amphibole-supergroup minerals is described, based on the general formula AB(2)C(5)T(8)O(22)W(2), where A = square, Na, K, Ca, Pb, Li; B = Na, Ca, Mn2+, Fe2+, Mg, Li; C = Mg, Fe2+, Mn2+, Al, Fe3+, Mn3+, Ti4+, Li; T = Si, Al, Ti4+, Be; W = (OH), F, Cl, O2-. Distinct arrangements of formal charges at the sites (or groups of sites) in the amphibole structure warrant distinct root names, and are, by implication, distinct species; for a specific root name, different homovalent cations (e.g., Mg vs. Fe) or anions (e.g., OH vs. Fe2+) are indicated by prefixes (e.g., ferro-, fluoro-). The Classification is based on the A, B, and C groups of cations and the W group of…