The International Mineralogical Association amphibole nomenclature scheme: computerization and its consequence.

A FORTRAN program has been written which inputs amphibole analyses, and outputs complete IMA-approved names, along with tabulated analyses, formula units, and IMA classification parameters. Several important corrections, additions, and amendments to the IMA scheme were found to be necessary. Two newly approved names have been incorporated—sadanagaite (ferro-pargasitic amphibole with Si AlVI, Si 2), or cation totals (e.g. T + C + B > 15), commonly reflecting low H2O determinations. These prevent strict obeyance of the IMA site occupancy calculation rules. This problem can often be overcome by recalculation free of H2O, but other cases require modifications to the IMA rules. In particular, ‘misclassification’ of certain sodic-calcic amphiboles as edenite follows from transferring large excesses of C cations to the B site