Mckelveyite-(Y)

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

Mckelveyite-(Y)
Mckelveyite-(Y) found in Canada
General
Category	Carbonate mineral
Formula	Ba3Na(Ca,U)Y(CO3)6·3H2O
IMA symbol	Mkv-Y[1]
Strunz classification	5.CC.05
Crystal system	Triclinic
Crystal class	Pedial (1) (same H-M symbol)
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
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
Other characteristics	Radioactive
References	[2][3][4]

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.^[5]

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.^[2] 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.^[6]

See also

• List of minerals
• List of minerals named after people