RABEJACITE, CA(UO2)4(SO4)2(OH)6-CENTER-DO T-6H2O, NEW URANYL AND CALCIUM-SULFATE FROM LODEVE, HERAULT, FRANCE

Rabejacite occurs as flattened tablets (up to 0.1 mm), acicular crysta ls or rounded nodules (up to 0.3 mm). Bright to amber yellow and trans parent to translucent with a vitreous luster. Light yellow fluorescenc e under short-wave and long-wave UV lights. Optically 2V (-) with alph a(calc) = 1.617, beta = 1.710, gamma = 1.758, 2V (meas.) = 68-degrees. Optical orientation, X = c, Y and Z in the plane of the tablets. Syst em orthorhombic, a = 8.73(1), b = 17.09(2), c = 15.72(2) angstrom, Z = 4, D(calc.) = 4.31 g/cm3, D(meas) greater-than-or-equal-to 4.10 g/cm3 . The strongest lines in the X-ray powder pattern are (d(angstrom),I,h kl) 7.90 (100) 002, 3.49 (80) 222 & 230, 3.38 (70) 231, 3.98 (40) 123, 4.17 (30) 201. The average of 20 electron-microprobe analyses gave: C aO 2.78%, UO3 76.62%, SO3 10.43%, H2O (by chromatography) 10.18%. Empi rical formula Ca0.76 (UO2)4.15(SO4)2.02(OH)5.78 . 5.86 H2O or ideally Ca(UO2)4(SO4)2(OH)6. 6H2O. Rabejacite was found in two deposits of the Permian basin of Lodeve: in the red Saxonian pelites from Rabejac (7 km S-SE from Lodeve) and in the gray Autunian from Mas d'Alary Village (3 km S-SE from Lodeve). The mineral appears in the alteration zone a nd forms mixed crusts together with gypsum. The name is for the locali ty of the first discovery.