Standard Uranium enters Wyoming

The Powder River Basin of northeastern Wyoming was previously one of the United States’ most prolific uranium camps, but weak markets in the 1980s meant the end of most productive mining there. Now, as prices rebound — at least nominally — to 1970s levels, at least one junior company has found its way back to the area to join the major uranium producers that had held on in the lean years.

Vancouver-based Standard Uranium (URN-V) has tied up about 10 sq. miles of claims in three areas of the basin: in the Kaycee area 60 miles north of Casper and in two areas around Pine Tree Junction 60 miles northeast. (It’s refreshing to note that the company staked the ground on its own account.) The claims either cover or tie on to known resources or uranium occurrences in the basin.

Uranium in the Tertiary-aged sandstones and sandy shales of the Wind River and Wasatch formations is a simple enough concept: groundwater dissolves uranium, and sometimes vanadium and molybdenum, from igneous rocks — typically tuff beds — and carries the metals through the gently dipping, permeable sandstones until it meets organic matter and pyrite that cause the metals to drop out of solution. But groundwater flow is not simple, and the geometry of the mineralization isn’t either: these are the storied “roll fronts” of the sandstones, shaped like a floor mat that has been slid on by a charging terrier.

The roll fronts’ footprints are broadly arc-like, extending into the basin from groundwater recharge areas at the edges. And it is along these fronts — perhaps 20 or 30 miles long, counting the twists and turns — that the mineral deposits are found.

Standard’s staking has followed that pattern, picking out ground along three known roll fronts: Kaycee, Pumpkin Buttes, and Turnercrest. These are all north of the principal Highland and Smith Ranch deposits, held by Cameco (CCO-T). At Kaycee, Standard has staked 3.5 sq. miles in two blocks, Geronimo and Tall Bull. Resource calculations, dating from 1982 and not meeting current standards, put the size of the uranium deposits on the two blocks at a total of 384,000 tons grading 0.085% U3O8.

Five claim blocks along the Turnercrest front all have some development drilling, but no calculated resource. One, the Longstreet block, is about 5 miles south of Cameco’s Ruby Ranch property, where the major is investigating the feasibility of an in situ leach operation to recover a reserve of 2.1 million tonnes grading 0.11% U3O8.

In the Pumpkin Buttes area, which saw some production in the 1980s, Standard has staked three claim groups, including one, Gettysburg, with some development drilling. There was previous production on the Pumpkin Buttes front, from the Irigaray and Christensen Ranch mines, both in situ leach operations now held by Cogema.