マンガン鉱床産含マンガンアルカリカルシウム角閃石の鉱物学的研究

抄録

Optical, chemical, X-ray and infrared studies on several manganoan alkali-calcic amphiboles from manganese ore deposits were performed. Optical properties are as follows: extinction angles are large (c∧X or c∧Z 30-44°) and dispersion is very strong (2 V_x=20-40° for yellowish species and 2 V_x = 30-88° for others). Al₂O₃ content is very small for the all amphiboles examined. Manganese is contained generally in smaller amounts than 2.0 per formula unit except for kozulite (3.7), and it distributes in M1·M2·M3 sites rather than in M 4 site. A site is occupied by alkali ions in vari-ous amounts. The spacing a_Osinß and cell volume increase in proportion to occupancies of alkali ions in the A site. Infrared OH stretching bands can be divided into two ranges: 3725-3680 cm^-1 and 3680-3640 cm^-1. The former bands may be shifted to the higher wave number side by the effects of alkali ions in the A site, and the intensity ratios to the latter bands are interpreted to be controlled by the A site occupancies of alkali ions. OH deformation (bending) bands appear also near 700 cm^-1 and near 600 cm^-1, and they are correlated with the oh stretching bands in a reversed frequency relation.