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 in order to simplify it, make it more consist ent with divisions generally at 50%, define prefixes and modifiers mor e precisely and include new amphibole species discovered and named sin ce 1978, when the previous scheme was approved. The same reference axe s form the basis of the new scheme and most names are little changed b ut compound species names like tremolitic hornblende (now magnesiohorn blende) are abolished and also crossite (now glaucophane or ferroglauc ophane or magnesioriebeckite or riebeckite), tirodite (now manganocumm ingtonite) and dannemorite (now manganogrunerite). The 50% rule has be en broken only to retain tremolite and actinolite as in the 1978 schem e so the sodic calcic amphibole range has therefore been expanded. Alk ali amphiboles are now sodic amphiboles. The use of hyphens is defined . New amphibole names approved since 1978 include nyboite, leakeite, k ornite, ungarettiite, sadanagaite and cannilloite. All abandoned names are listed. The formulae and source of the amphibole end member names are listed and procedures outlined to calculate Fe3+ and Fe2+ when no t determined by analysis.