Gypsum and complex sulphide ore deposits of Yonaihata Mine, northern Aizu district, occur in the Tertiary grayish black shale of Yonaihata series. Complex sulphide ore consists of sphalerite, chalcopyrite, pyrite and galena and is included as irregular shaped mass in the rich parts of gypsum ore. The metallic ores are intimately paragenited as seen in Fig. 3, and the liberation of the ore minerals is comparatively difficult as shown in Table 10 and Figs. 6 and 7. Crushing and grinding characters were tested and the results are shown in Table 11 and Figs. 8 and 9
