Name:  Quartzite

Geologic Name:  Sioux Quartzite

Reference:  Todd, J.E, Geology and water resources of a portion of
southeastern South Dakota: U.S. Geol. Survey Water Supply Paper 34,
1900.

Microscopic characters:  The rock is composed of rounded and sub-
angular quartz grains with a siliceous cement which is in part
granular and in part in optical continuity with the original quartz
grains.