Chemistry:Mckelveyite-(Y)

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Mckelveyite-(Y)
Mckelveyite-(Y).jpg
Mckelveyite-(Y) found in Canada
General
CategoryCarbonate mineral
Formula
(repeating unit)
Ba3Na(Ca,U)Y(CO3)6·3H2O
Strunz classification5.CC.05
Crystal systemTriclinic
Crystal classPedial (1)
(same H-M symbol)
Space groupP1
Unit cella = 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
ColorLime-yellow, greenish gray, reddish brown, may be black from contained organic material
Crystal habitTabular, pyramidal
TwinningThreefold (pseudorhombohedral about {0001})
CleavageIndistinct
Mohs scale hardness3.5–4
|re|er}}Vitreous, greasy, or dull
StreakWhite
DiaphaneityTransparent to opaque
Specific gravity3.25
Optical propertiesBiaxial (-)
Refractive indexnα = 1.550–1.554 nβ = 1.550–1.554 nγ = 1.649–1.658
Birefringenceδ 0.0990–0.1040
PleochroismVisible
Other characteristicsRadioactive.svg Radioactive
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

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

References

  1. 1.0 1.1 1.2 Anthony, John W.; Richard A. Bideaux; Kenneth W. Bladh; Monte C. Nichols (1995). Handbook of Mineralogy. Tucson, Arizona: Mineral Data Publishing. ISBN 978-0-9622097-1-0. http://www.handbookofmineralogy.org/pdfs/mckelveyitey.pdf. 
  2. 2.0 2.1 "Mckelveyite-(Y)". webmineral.com. http://webmineral.com/data/Mckelveyite-(Y).shtml. Retrieved 2008-12-13. 
  3. Mckelveyite-(Y) on Mindat.org
  4. Milton, C.; B. Ingram; J.R. Clark; E.J. Dwornik (1965). "Mckelveyite, a new hydrous sodium barium rare-earth uranium carbonate mineral from the Green River Formation, Wyoming.". Am. Mineral. 50: 593–612. http://www.minsocam.org/ammin/AM50/AM50_593.pdf. 
  5. Mindat