Stichtite from Furuyasiki, Iizuka, Fukuoka Prefecture

Abstract

There are many carbonate veins in serpentinite at Furuyasiki, Fukuoka Prefecture, Japan. In veins, hydrotalcite group minerals occur, which are purple, white and brown. In this research, we mainly analyzed the purple one, and stichtite from Dundas, Tasmania, Australia for comparison. Purple hydrotalcite group mineral from Furuyasiki is stichtite, and occurs as plates around chromite in serpentinite, which is contained in dolomite veins. As a result of the analysis, formulae of stichtite were Mg_6.09(Cr_1.55Fe_0.39)CO₃(OH)₁₆ 4H₂O (Furuyasiki) and Mg_6.07(Cr_1.17Fe_0.62Al_0.07Si_0.06)CO₃(OH)₁₆ 4H₂O  (Dundas). From X ray diffraction pattern, stichtite from Furuyasiki had 3R polytype.