Ellsworthite

Uranpyrochlore (of Hogarth 1977), also known as ellsworthite or betafite (Ca,U)2(Ti,Nb,Ta)2O6(OH), is a rare earth mineral mostly found in the northern parts of North America. It is a uranpyrochlore and is named after Hardy V. Ellsworth of the Canadian Geological Survey by Walker and Parsons. It is a very uranium- and thorium- rich mineral, which in fact makes it slightly radioactive. Uranium makes up about 17.1% of the mineral. Ellsworthite is also known as the mineral Betafite. Ellsworthite is a thorium-bearing mineral that is found mostly in Canada and Alaska. It was first discovered in Hybla, Ontario, which is now a ghost town.

Composition
Ellsworthite has complex hydrous oxides of niobium, tantalum, sodium, calcium, with hydroxyl and fluorine; it may contain as much as 17% uranium.

Structure
The structure of ellsworthite is cubic and has a point group of 4/m 3* 2/m. It is part of the isometric system and has the space group Fd3m. It forms into a Hexoctahedral with {110}, {100}, {113}, {233}, and {230}.