Chromioamphibole from the Akaishi chrom deposit, Ehime Pref.

Abstract

Chromioamphibole found from the Akaishi chromdeposit and occurred as prismatic crystal up to 1cm length,associated with chromiandiopside, kammererite and phlogopite. Results SEM-EDS analysis gave SiO2 42.90,TiO2 0.25, Al2O3 12.10, Cr2O35.46,Fe2O3 1.20,MnO0.00,MgO19.28, CaO 12.31,Na2O 3.26, K2O 0.37,H2O 2.09(Calc.) Total 99.22wt%, corresponding to (K0.07Na0.87)(Na0.05Ca1.89) Mg4.11 (Fe0.13 Al0.18 Ti0.03 Cr0.62)(Al1.86 Si6.14)O22(OH)2, ideally NaCa2Mg4Cr(Al2Si6) O22(OH)2. This mineral is a Cr-analogue of pargasite or magnesiohastingsite