Markeyite
A uranyl carbonate from Utah's Markey mine, structurally solved by Anthony Kampf's team in Los Angeles.
Intro adapted from Wikipedia (CC BY-SA).
Markeyite is an IMA-recognized mineral species in the carbonate class, with the chemical formula Ca₉(UO₂)₄(CO₃)₁₃·28H₂O.
It crystallizes in the orthorhombic crystal system (space group Pmmn). It is a member of the Markeyite structural group.
Key properties: Mohs hardness 1.5–2; specific gravity 2.68; White streak; Vitreous luster; optically biaxial.
IMA symbol Mk, IMA status: approved, named in 2017.
Occurs as efflorescent crusts on the surfaces of mine walls in a Colorado Plateau-type, roll front uranium deposit.
It is found associated with Asphaltum, calcite, gypsum, natrozippeite.
The name is derived from the locality, the Markey mine.