Abstract
Diopsidic to hedenbergitic clinopyroxenes are major constituent minerals both in the country rocks called Inishi Migmatite and skarn ore in the Kamioka Pb-Zn deposits embedded in intercalated marble beds within the Hida gneisses, central Japan. Clinopyroxenes in the Inishi Migmatite generally vary from Hd (hedenbergite molecule percent) 40 to 70, mostly 50 to 60 in composition, and those in the skarn ore called Mokuji ore range from Hd70 to larger than 90 with higher johannsenite molecule (10 to 20%) than the former (generally less than 3%). The replacement of marble beds by the hedenbergitic skarn requires significant enrichment of iron, however, there can be found no systematic compositional change in clinopyroxenes of the country rocks around orebodies, in any scale of investigations from regional to an outcrop. Clinopyroxenes vary randomly in composition from a specimen to specimen, and the increase of Hd-molecule is limited in the narrow zone of hydrothermally altered part nearest the orebody, such as called "Yopparai". The composition of clinopyroxenes in the country rocks is essentially controlled by the difference of bulk chemistry, not by the mineralization, and it is likely that the Inishi Migmatite did not directly relate to the mineralization.
