Abstract
Chemical composition and crystal structure of babingtonite from Kouragahana, Shimane Peninsula, were investigated. The babingtonite crystals are black in color and rhombic in shape. They show sector zoning and zonal structure. Fe content increases from core to margin, whereas Mn and Al decrease. Each sector contains different amounts of Fe and Mn. Average chemical formula is as follows: (K0.004Na0.006Ca2.009)(Mg0.113Mn0.094Fe1.696Ni0.002V0.003Cr0.001Ti0.009Al0.058)Si5.005O14(OH). The Mossbauer spectrum consists of two doublets by Fe2+ and Fe3+. The Fe2+:Fe3+-ratio is 45:55. The crystal structure was refined using X-ray Rietveld method. The refined Fe occupancies at two different octahedral sites are 0.74 and 0.92, respectively, which is consistent with the results using Mossbauer method.
