| Abstract |
The Zomeki adit of Kusugi mine, situated about 18 kilometers west of the Iwakuni City, works on a few manganese ore deposits found in Paleozoic chert and slate. The material examined were obtained as ...long needles ca. 3cm long, in quartz-rich portions of the deposit, associated with abundant grains of spessartine (a。=11.62A, d= 4. 11). The specific gravity measured was 3. 30 at 28°C by pycnometer. The optical properties were as follows; α=1 . 648, β=1 . 661, γ= 1 . 672, cZ =1 9°, 2V(-) =8 8°The chemical composition was analysed; SiO_2 51. 34, Al_2O_3 1.44, Fe_2O_2 2.29, FeO 13.55, MnO 14.04, MgO 13.28, CaO 3.00, H_2O+ 1.06, H_2O^- 0.15, total 100.15%. It shows a remarkably high manganese content as a mineral of the cummingtonite group. The X-ray diffraction patterns are, however, in good accordance with those reported by Johansson.show more
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