Book Description

Nine uranium deposits occur in a small area west of Clancey, Jefferson County, Mont. These deposits are all in or near silicified fracture zones in quartz monzonite and related rocks of the Boulder batholith. The deposits contain pockets of uranium minerals in cavities in brecciated silicified rock. The primary uranium mineral pitchblende has been found in one pod. Secondary uranium minerals occur as fracture linings and in pore spaces in and adjacent to silicified zones. Uranium in the Clancey district was deposited probably during one of the later of at least four periods of silicification. The quartz monzonite, rather than the younger alaskitic dike rocks, is the host rock of the deposits.