Mckelveyite-(Y)

From Wikipedia, the free encyclopedia
  (Redirected from Mckelveyite)
Jump to: navigation, search
Mckelveyite-(Y)
General
Category Carbonate mineral
Formula
(repeating unit)
Ba3Na(Ca,U)Y(CO3)6·3H2O
Strunz classification 05.CC.05
Crystal symmetry Triclinic
H-M symbol: 1 - Pedial
Space group: P1
Unit cell a = 9.170(3) Å, b = 9.169(3) Å, c = 7.075(2) Å; α = 102.50(3)°, β = 115.63(3)°, γ = 59.99(3)°; Z=1
Identification
Color Lime-yellow, greenish gray, reddish brown, may be black from contained organic material
Crystal habit Tabular, pyramidal
Crystal system Triclinic
Twinning Threefold (pseudorhombohedral about {0001})
Cleavage Indistinct
Mohs scale hardness 3.5–4
Luster Vitreous, greasy, or dull
Streak White
Diaphaneity Transparent to opaque
Specific gravity 3.25
Optical properties Biaxial (-)
Refractive index nα = 1.550–1.554 nβ = 1.550–1.554 nγ = 1.649–1.658
Birefringence δ 0.0990–0.1040
Pleochroism Visible
References [1][2][3]

Mckelveyite-(Y) is a hydrated sodium, barium, yttrium, and uranium–containing carbonate mineral, with the chemical formula Ba3Na(Ca,U)Y(CO3)6·3H2O.[1][2]

Occurrence[edit]

It was first described in 1965 from deposits in the Green River Formation, Sweetwater County, Wyoming, and is named after Vincent Ellis McKelvey (1916–1985), a former director of the United States Geological Survey.[4]

It occurs associate with trona layers in the Green River Formation of Wyoming and has been reported from an alkalic intrusive, the Khibiny Massif in the Kola Peninsula of Russia. It occurs in association with ewaldite, acmite, biotite, quartz, labuntsovite, searlesite and leucosphenite in the Green River Formation. In the Khibiny Massif it occurs with ewaldite, belovite-(Ce), fluorite, nenadkevichite, ancylite-(Ce), synchysite-(Ce), kukharenkoite-(Y), burbankite, calcite, barite and orthoclase. In the Khanneshin complex, Afghanistan it occurs with dolomite, calkinsite-(Ce), carbocernaite, khanneshite and barite.[1] It has also been reported from the Mont Saint-Hilaire intrusive complex in Quebec.

A related neodymium-rich mineral, mckelveyite-(Nd) has been described for an occurrence in the Vuoriyarvi alkaline-ultrabasic massif on the Kola Peninsula. However, the mineral has not been approved by the IMA.[5]

See also[edit]

References[edit]

  1. ^ a b c Anthony, John W.; Richard A. Bideaux, Kenneth W. Bladh, and Monte C. Nichols (1995). Handbook of Mineralogy. Tucson, Arizona: Mineral Data Publishing. ISBN 978-0-9622097-1-0. 
  2. ^ a b "Mckelveyite-(Y)". webmineral.com. Retrieved 2008-12-13. 
  3. ^ Mckelveyite-(Y) on Mindat.org
  4. ^ Milton, C.; B. Ingram, J.R. Clark, and E.J. Dwornik (1965). "Mckelveyite, a new hydrous sodium barium rare-earth uranium carbonate mineral from the Green River Formation, Wyoming.". Amer. Mineral. 50: 593–612. 
  5. ^ Mindat