Chinleite-(Ce), NaCe(SO4)2(H2O), a New Mineral from the Blue Streak Mine, Montrose County, Colorado, USA

Abstract Chinleite-(Ce) (IMA2024-009), NaCe(SO4)2(H2O), is a new mineral discovered as a secondary phase on a tunnel wall in the Blue Streak mine, Bull Canyon, Montrose County, Colorado, USA. It occurs as colorless prisms growing on a veneer of phlogopite in association with boltwoodite, gypsum, hummerite, and mathesiusite. Crystals are transparent with vitreous luster and white streak. The Mohs hardness is 2½–3. The mineral has brittle tenacity, splintery fracture, and one good cleavage (probably on {100}). The calculated density is 3.149 g/cm3. Electron probe microanalysis provided the empirical formula (Na0.621Ca0.488Ce0.243Nd0.222K0.180Sr0.078Pr0.048La0.046Sm0.035Gd0.032Eu0.012)Σ2.005[SO3.922(OH)0.078]2(H2O). Chinleite-(Ce) is trigonal, P3221, a = 7.0211(11), c = 12.942(3) Å, V = 552.5(2) Å3, and Z = 3. Chinleite-(Ce) is the Ce analogue of chinleite-(Y) and chinleite-(Nd).