Abstract

In 2004, the International Mineralogical Association (IMA) amended the IMA 97 amphibole classification and nomenclature scheme by adding a fifth group to include the recently discovered B(LiNa) amphiboles ferriwhittakeriite and ferri-ottoliniite, which cannot be fitted into the four major amphibole groups. New root-names such as sodic-pedrizite in the Mg-Fe-Mn-Li group and obertiite and dellaventuraite in the sodic group along with two new prefixes, parvo and magno have also been added. As result it has become necessary to modify the AMPH-IMA97 amphibole-naming program. The new program (AMPH-IMA04) allows single input or automatic input of as many amphibole analyses as are available following a set input format. Any of three different calculation schemes for dealing with an amphibole analysis can be chosen: (1) complete chemical analyses can be calculated to 24(O,OH,F,Cl); (2) analyses with determined FeO and Fe2O3, MnO and Mn2O3 but without H2O can be calculated to 23(O); and (3) electron microprobe analyses with only total Fe determined and without H2O can be calculated to 23(O) with IMA97-recommended normalization for Fe3+ and Fe2+ values. In addition a stoichiometric calculation of Mn2+ and Mn3+ is considered and implemented for the Mn-bearing sodic amphiboles in order to take care of electron microprobe analyses of such amphiboles where the total Mn is given as Mn2+.

You do not currently have access to this article.