This is the largest surface boulder of Diaspore found in the Missouri Diaspore Fields south of the Missouri River. It was taken from a diaspora pit near Aud, Osage County, Missouri, in 1926. Diaspore is a high alumina clay occurring in this form with a fusion point above 3300°F. Chemically, it consists mainly of alumina and water. Diaspore is a raw material or clay from which the A. P. Green high alumina super refractories are made.