Uranpyrochlore

specimen number:
2354193

location:
McDonald Mine, Hybla, Ontario, Canada

description:
Very rich lustrous brown masses of uranpyrochlore throughout matrix. The specimen comes with an old label from Western Minerals in Rialto, California. Good example for the species.

Located near Hybla in Ontario, Canada, the Macdonald Mine was a massive granitic pegmatite deposit operated primarily for feldspar mining from 1919 until the 1930s. Geologically, the complex zoned pegmatite hosted numerous rare and unusual accessory minerals within its massive quartz and calcite cores. Among these notable phases was uranpyrochlore, a complex radioactive oxide mineral historically referred to at the site by variety names like ellsworthite, which formed waxy brown or black masses embedded within the rock. Although commercial operations ceased long ago and the underground workings have since been heavily rehabilitated and closed off, the site remains famous among mineral collectors and researchers for its rich assemblage of unusual radioactive and rare-element specimens.

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