Large Twinned Uraninite Crystals - Cardiff Uranium Mine, near Bancroft, Ontario

A specimen of large uraninite crystals from the Cardiff Uranium Mine, one of the better-known producers in the Bancroft district. The standout is a larger twinned crystal, a distinctive feature in a species that most often turns up as simple octahedra or cubes. The crystals show the deep black color and bright submetallic luster that define uraninite, and their size is a clear step up from the small grains and crusts more typical of the region.

Twinning in uraninite is an uncommon and sought-after habit, and a twin of this scale makes the piece far more interesting than a standard crystal specimen. Cardiff was part of Ontario’s mid-century uranium boom, and the mine’s pegmatitic ore produced well-formed uraninite that continues to draw collectors of Canadian radioactive minerals. Like the other historic Bancroft-area mines, it is long out of production, and large crystals with firm locality data are increasingly hard to find.

A standout piece for a Canadian uranium collection, a crystal habit suite, or a display of classic Bancroft-area localities.

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Approx. specimen activity on an SE International Ranger EXP: 83 000 CPM