On the Gypsum Deposits in Shimane Prefecture (I)

概要

論文の詳細を見る
Shimane Prefecture is the biggest producer of gypsum ore in Japan; its production of concentrated gypsum ore (average grade is 30-34% of SO3) in 1956 is about 140, 000 tons which occupies 36% of whole gypsum production in Japan. There are two groups of gypsum deposits in the prefecture; (1) Yama region of Central Shimane and (2) Hikawa region at the north-western Shimane Peninsula and ten mines are in work. Geological feature of these region comprise Miocne "Green tuff", composed of volcanic pyroclastics, with black shale, covered unconformably by basaltic and rhyolitic flows, and sandstone beds. The gypsum ore deposits occur in the alternation of rhyolitic tuff or tuff breccia and black shale as erregularly lenticular or massive bodies, The black ore (Zn, Pb and Cu ores) deposits occur in black shale as vein-like or network form. Wall rock alternations are characteristically chloritization, sericitization, montmorillonitizations and pyritization. Textures of the gypsum ore are classified megascopically as (i) massive ore, (ii) banded ore, (iii) brecciated ore and (iv) pisolitic ore. Among them, the brecciated and massive onrs are the most common. These ores mostly consist of alabaster, satin gypsum and small amount of calcite, barite and sporadic-spread of fine pyrite. The results of the former analyses of the refined ores show 30-34% of SO3.
無機マテリアル学会の論文