This monster 11.8-pound uranium ore block is one of the largest pieces we’ve offered.
Measuring 10 × 6 × 3.5 inches, it features an entire face coated in rich yellow uranium secondary minerals with a peak reading of 50,000 CPM on that side alone.
The opposite face reads 5,000 to 25,000 CPM and shows the oxidized host sandstone that produced this spectacular mineral bloom.
The bright yellow surface is likely a mix of:
Uranophane
Zippeite
Other secondary uranium oxides/hydrates
These minerals form when primary uranium (often uraninite) oxidizes and moves through porous rock, depositing vibrant crusts. Pieces like this — large, stable, and hot on one face — are rare and highly sought after for educational displays, Geiger counter demos, and private mineral collections.
Weight: 11 lbs 13 oz
Peak radiation: 50,000 CPM
Average radiation: 5,000 bottom CPM 30,000 top CPM
Dimensions: 10 × 6 × 3.5 inches
Origin: Gateway Colorado
This monster 11.8-pound uranium ore block is one of the largest pieces we’ve offered.
Measuring 10 × 6 × 3.5 inches, it features an entire face coated in rich yellow uranium secondary minerals with a peak reading of 50,000 CPM on that side alone.
The opposite face reads 5,000 to 25,000 CPM and shows the oxidized host sandstone that produced this spectacular mineral bloom.
The bright yellow surface is likely a mix of:
Uranophane
Zippeite
Other secondary uranium oxides/hydrates
These minerals form when primary uranium (often uraninite) oxidizes and moves through porous rock, depositing vibrant crusts. Pieces like this — large, stable, and hot on one face — are rare and highly sought after for educational displays, Geiger counter demos, and private mineral collections.
Weight: 11 lbs 13 oz
Peak radiation: 50,000 CPM
Average radiation: 5,000 bottom CPM 30,000 top CPM
Dimensions: 10 × 6 × 3.5 inches
Origin: Gateway Colorado
