Miocene-Pliocene lignite and sub-bituminous coal strata spread over about 600 square km of northeastern Yamagata. At least 70 mines worked these coal beds, 0.7 to 2 meters thick, with over 135 million tons of reserves.
The coal here is enriched in germanium - up to 102.5 ppm. The Ge is concentrated in the vitrain component and has been commercially recovered from coal gas.
Mineral List:No entries listed.
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