NOMENCLATURE OF AMPHIBOLES - REPORT OF THE SUBCOMMITTEE ON AMPHIBOLESOF THE INTERNATIONAL-MINERALOGICAL-ASSOCIATION, COMMISSION ON NEW MINERALS AND MINERAL NAMES

The International Mineralogical Association's approved amphibole nomen clature has been revised to simplify it, make it more consistent with divisions generally at 50%, define prefixes and modifiers more precise ly, and include new amphibole species discovered and named since 1978, when the previous scheme was approved. The same reference axes form t he basis of the new scheme and most names are little changed, but comp ound species names like tremolitic hornblende (now magnesiohornblende) are abolished, as are crossite (now glaucophane or ferroglaucophane o r magnesioriebeckite or riebeckite), tirodite (now manganocummingtonit e), and dannemorite (now manganogrunerite). The 50% rule has been brok en only to retain tremolite and actinolite as in the 1978 scheme; the sodic-calcic amphibole range has therefore been expanded. Alkali amphi boles are now sodic amphiboles. The use of hyphens is defined. New amp hibole names approved since 1978 include nyboite, leakeite, kornite, u ngarettiite, sadanagaite, and cannilloite. AU abandoned names are list ed. The formulae and source of the amphibole end-member names are list ed and procedures outlined to calculate Fe3+ and Fe2+ where not determ ined by analysis.