Skeletal crystals of sphalerite in chalcopyrite

Under the microscope, skeletal crystals of sphalerite are found in chalcopyrite from the Kawayama, Oya, Ashio and Daira mines. They are belived as due to exsolution of a solid solution. The writers have made thermal studies on skeletal crystals of sphalerite. No change of skeletal crystals of sphalerite in chalcopyrite is found at 4OO°C for 24 hours. At temperatures from 425°C to 450°C for 24 hours, the skeletal crystals are absorbed partly by chalcopyrite, and disappear completely at 480°C for 48 hours (Oya), at 500°C for 24 hours (Kawayama), at 500°C for 48 hours (Daira) and at 515°C for 24 hours (Ashio). The solid solutions of chalcopyrite and sphalerite, obtained by heating at temperatures from 475°C to 530°C, show slightly the unmixing process at various constant temperatures from 200°C to 400°C for 24 hours. The sphalerite, then, appears in fine worm-like, drop-shaped or skeletal crystals.