Dry Screening manganese ore fragments from the soil at the C.F.I. mine, southeast of Green River. Grand County, Utah. 1918.

Dry Screening manganese ore fragments from the soil at the C.F.I. mine, southeast of Green River. Much of the manganese ore produced in this region is found as loose fragments that commonly range in size from that of a peanut to that of a base ball. In places these fragments rather closely pave the surface, generally they are mixed with a foot, more or less, of loose sandy soil. These ore fragments were originally parts of a thin horizontal bed of manganese oxides. Lowering of the surface by erosion, in which wind deflation has played a large part, exposed the manganiferous layer that became broken into fragments but was not comminuted sufficiently to be removed by the wind. As the more friable sandstone that adjoins the bed was gradually [...]