General Atomics' subsidiary Rio Grande Resources is currently evaluating its Mt. Taylor Mine for development by in-situ leaching. Uranium is present in coffinite in the Westwater Canyon member of the Morrison Formation at 3,000 feet (900 m) below ground surface. The mine, which operated as an underground uranium mine from 1986 to 1989, has a remaining resource estimated by its owner at more than 45 thousand tonnes of uranium oxide.