Yellow rounded crystal of the very rare yttrium mineral mckelveyite-(Y) from the famous Mont Saint Hilaire (Québec, Canada). — Photo: David Hospital · CC BY-SA 4.0
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.
Intro adapted from Wikipedia (CC BY-SA).
Mckelveyite-(Y) is an IMA-recognized mineral species in the carbonate class, with the chemical formula NaBa₃CaY(CO₃)₆·3H₂O.
It crystallizes in the monoclinic crystal system (space group Cc). It is a member of the Mckelveyite structural group.
Key properties: Mohs hardness 3.5–4; specific gravity 3.25; Vitreous to dull luster; refractive index 1.587; optically uniaxial.
IMA symbol Mkv-Y, IMA status: approved, named in 1964.
A rare mineral formed near trona beds in the Green River Formation (Wyoming, USA); in a differentiated alkalic massif (Khibiny massif, Kola Peninsula, Russia).
It is found associated with Ewaldite, acmite, “biotite”, quartz, labuntsovite, searlesite, leucosphenite (Wyoming, USA); ewaldite, belovite-(Ce), fluorite, nenadkevichite, ancylite-(Ce).
The mineral was named to honor Vincent Ellis McKelvey (1916–1985), Director of the U.S. Geological Survey, Washington, D.C., USA, for his studies of the Phosphoria Formation of Wyoming and Idaho, USA.