Diaspore (Burly Clay). From the mineral collection of Brigham Young University Department of Geology, Provo, Utah, Mineral Specimens 459. Courtesy of the U.S. Geological Survey Denver Library Photographic Collection. (Photo by Andrew Silver.)

Formula: AlO(OH) Orthorhombic


Diaspore occurs as platy masses in highly aluminous metamorphic rocks associated with corundum. It is a common component of emery. Diaspore also is a common component of bauxite, aluminous soils and clays.

BARRON COUNTY: Dott and Dalziel (1972) report diaspore as a component of pipestone in the Blue Hills area where it is intergrown with kaolin, illite and quartz.

SAUK COUNTY: diaspore is a component of the metasaprolite and in veins at the base of the Baraboo Quartzite. Here is occurs with pyrophyllite, kaolin and muscovite. (Medaris and Dott, 2001).