AMPH-IMA97: a hypercard program to determine the name of an amphibole from electron microprobe and wet chemical analyses

Abstract

In 1997, the International Mineralogical Association (IMA) revised the amphibole naming scheme making it necessary to amend the previous EMP-AMPH Macintosh program to the new rules. The AMPH-IMA97 program allows single input or automatic input of as many amphibole analyses as are available following a set input format. There are three options for calculation scheme of amphibole analysis: (1) complete chemical analyses can be calculated to 24(O, OH, F, Cl); (2) analyses with determined FeO and Fe 2O 3 but without H 2O can be calculated to 23(O) and (3) electron microprobe analyses with only total Fe determined and without H 2O can be calculated to 23(O) with IMA97-recommended normalization for Fe 3+ and Fe 2+ values. To test the program, over 500 analyses were calculated using the three options. The first comprehensive test of the third option successfully estimated Fe 2+ ( R 2=0.88), but became less successful for Fe 3+ ( R 2=0.42) estimation. Problems in the normalization of Mn 3+- and Mn 2+-bearing amphiboles and in the IMA97 sodic amphibole classification procedure emerged for Mn-rich amphiboles. This necessitated the proposal and implementation with the program of a simplified sodic amphibole classification scheme. A new coloured amphibole classification chart accompanies the program.