Ellsworthite

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Uranpyrochlore
(of Hogarth 1977)
General
CategoryPyrochlore group
Formula
(repeating unit)
(Ca,U)2(Ti,Nb,Ta)2O6(OH)
Crystal systemisometric
Space groupCubic 4/m 3* 2/m
Identification
Coloramber yellow to dark brown; translucent or opaque
CleavageNone
Fractureconchoidal fracture
Mohs scale hardness5.5
Lustervitreous
Streakyellow to brownish[1]
Other characteristics Radioactive
References[1][2]

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.[3] 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.[4] 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.[2]

Composition[edit]

Ellsworthite has complex hydrous oxides of niobium, tantalum, sodium, calcium, with hydroxyl and fluorine; it may contain as much as 17% uranium.[5][1][6]

Structure[edit]

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}.[1]

Sources[edit]

  1. ^ a b c d "Betafite" (PDF). The Handbook of Mineralogy. Retrieved 21 October 2013.
  2. ^ a b Frodel, Clifford. (1958). Systematic Mineralogy of Uranium And Thorium, Geological survey bulletin 1064 pg.326-330
  3. ^ T. L. Walker and A. L. Parsons (1923) Ellsworthite and associated minerals from Hybla, Ontario. Contrib. Canad. Min., 1923, Univ. Toronto Stud., Geol. Ser., 16, 13-20
  4. ^ Frondel, J.W., Fleischer, M. (1950) A Glossary of Uranium-and Thorium-Bearing minerals. Geological Survey Circular 74, pg.11, http://babel.hathitrust.org/cgi/pt?id=uc1.32106020887797;view=1up;seq=1
  5. ^ Bates, R.G., Wedow Jr, H. (1953). Preliminary summary review of Thorium-Bearing mineral occurrence in Alaska. Geological Survey bulletin 202
  6. ^ Hogarth D.D. (1961) A study of Pyrochlore and Betafite, volume 6, issue 5. Canadian Mineralogist pg.610