Species: Uraninite, Rutherfordine, ‘Gummite’
Locality: Uluguru Mountains, Morogoro Region, Tanzania
Dimensions: 2.5 x 2.5 x 2.3 cm. (40 grams)
Ex. David P. Wilber Collection
The Uluguru Mountains of Tanzania area a remote but classic locality for rare uranium minerals, which occur in pegmatites here. This is a killer example of LARGE and well-formed cubic uraninite crystals which are being replaced by rutherfordine (Uluguru is the type locality for this mineral) and “gummite.” Measures ~150,000 CPM on my Ludlum Model 3 Counter with 44-9 probe. Rare!!