Uraninite - Grants District, New Mexico USA

UO₂

Uraninite from the Grants District in New Mexico is a primary uranium ore mineral, typically occurring as dense, black, metallic masses with a submetallic to greasy luster. It is composed primarily of uranium dioxide (UO₂) but often contains variable amounts of lead, thorium, and rare earth elements due to radioactive decay. The uraninite from this region is commonly associated with roll-front sandstone-hosted uranium deposits, where it precipitated from uranium-rich groundwater under reducing conditions. Its high radioactivity makes it a valuable economic source of uranium, historically fueling the region’s significance as one of the most prolific uranium-producing areas in the United States.

The Grants District, located in the San Juan Basin of northwestern New Mexico, was the center of American uranium mining from the 1950s to the 1980s, with uraninite being a primary ore mineral extracted from the region’s vast uranium deposits. The mineral commonly occurs in association with coffinite, pyrite, carbonaceous material, and various clay minerals within the sandstone matrix. Due to its uranium content, uraninite specimens from the Grants District are highly radioactive and require careful handling and storage. While large-scale mining has largely ceased, the district remains a significant historical and geological site, attracting interest from collectors, researchers, and those monitoring the potential for future uranium resource development.

Approx. specimen size: 25mm x 20mm x 12mm

Approx. specimen activity on an SE International Ranger EXP: 12 000 cpm

Specimen comes mounted in pictured membrane box.