Vorlanite, (CaU6+)O4, from Jabel Harmun, Palestinian Autonomy, Israel

Abstract

Vorlanite (CaU 6+ )O 4 [ Fm 3 m , a = 5.3647(9) A, V = 154.40(4) A 3 , 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 [ Fm 3 m , a = 5.3813(2) A, V = 155.834(10)A 3 , 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 CaUO 4 . The unusual color of vorlanite from Jabel Harmun is assumed to be related to small impurities of tetravalent uranium.