Abstract

Vanarsite (IMA2014-031), NaCa12(As3+V4+3.5V5+8.5As5+6O51)2·78H2O, packratite (IMA2014-059), Ca11(As3+V4+2V5+10As5+6O51)2·83H2O, morrisonite (IMA2014-088), Ca11(As3+V4+2V5+10As5+6O51)2·78H2O, and gatewayite (IMA2014-096), Ca6(As3+V4+3V5+9As5+6O51)·31H2O, are four new minerals from the Packrat mine, Gateway district, Mesa County, Colorado, U.S.A. Crystals of all four new minerals are very dark blue to greenish-blue blades. They are found together on montroseite- and corvusite-bearing sandstone in association with pharmacolite. Vanarsite is monoclinic, P21/c, a 25.8902(8), b 10.9468(3), c 28.2980(8) Å, β 102.252(1)°, V 7828.9(3) Å3, and Z = 2. Packratite is triclinic, Pforumla, a 18.0572(4), b 19.4126(4), c 24.0586(17) Å, α 87.364(6), β 86.266(6), γ 79.267(6)°, V 8263.4(7) Å3, and Z = 2. Morrisonite is monoclinic, P21/c, a 14.9566(18), b 48.208(6), c 23.836(3) Å, β 90.034(6)°, V 17187(4) Å3, and Z = 4. Gatewayite is monoclinic, P21, a 11.1850(4), b 16.8528(4), c 20.7146(15) Å, β 91.166(6)°, V 3903.9(3) Å3, and Z = 2. The structures of all four new minerals contain the novel polyoxometalate-like heteropolyanion, [As3+As5+6V4+2+xV5+10–xO51](11+x)– (x = 0 to 1.5), which is new to science.

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