長野県茅野市諏訪鉱山産コニンク石 <Bull. Natn. Sci. Mus., Tokyo>Koninckite from the Suwa Mine, Chino City, Nagano Prefecture, Japan

Koninckite from the Suwa mine occurs as aggregates of globules in a limonitic goethite ore and in a jarosite ore, Ores are the products of hydrothermal precipitation from an acidic hot spring on andesitic lavas and pyroclastics belonging to Yatsugatake volcanic rocks. The microprobe analysis of an aluminum-richer band in a globule of the former occurrence gives Fe_2O_3 35.73,Al_2O_3 2.52,P_2O_5 35.16,H_2O (by difference) 26.59,yielding the empirical formula (Fe_<0.90>Al_<0.10>)_<Σ1.00>P_<1.00>O_<4.00>・2.98 H_2O. The associated jarosite is phosphatian with P_2O_5 up to 4.54 wt.%. X-ray powder diffraction pattern is indexed on a tetragonal cell with a=11.977 (2), c=14.625 (2) A, Z=16,validating the previous results. The refractive index n=1.669 (2) with very low birefringence is slightly higher than the average of the material from the original locality.