Abstract

Vorlanite (CaU6+)O4 [Fmm, a = 5.3647(9) Å, V = 154.40(4) Å3, Z = 2] was found in larnite pyrometamorphic rocks of the Hatrurim formation at the Jabel Harmun locality, Judean Desert, Palestinian Autonomy. Vorlanite crystals from these larnite rocks are dark-gray with greenish hue in transmitted light. This color in transmitted light is in contrast to dark-red vorlanite [Fmm, a = 5.3813(2) Å, V = 155.834(10)Å3, Z = 2] from the type locality Upper Chegem caldera, Northern Caucasus. Heating above 750 °C of dark-gray vorlanite from the Jabel Harmun, as well as dark-red vorlanite from Caucasus, led to formation of yellow trigonal uranate CaUO4. The unusual color of vorlanite from Jabel Harmun is assumed to be related to small impurities of tetravalent uranium.

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