Original paper
La fontanite, carbonate hydraté d' uranyle et de calcium, nouvelle espèce minérale de Rabejac, Hérault, France
Deliens, Michel; Piret, Paul
European Journal of Mineralogy Volume 4 Number 6 (1992), p. 1271 - 1274
6 references
published: Dec 8, 1992
manuscript accepted: Apr 23, 1992
manuscript received: Dec 30, 1991
DOI: 10.1127/ejm/4/6/1271
Abstract
Abstract Fontanite from Rabejac occurs as elongated rectangular lath-shaped crystals. Bright yellow and trans- parent with a vitreous luster. Light green fluorescence under long-wave UV light. Optically 2V(-) with α = 1.603 (calc.), p = 1.690; γ = 1.710, 2V(meas.) = 49°. Optical orientation: X = b, Y = a and Z = c. System orthorhombic, space group Pmnm, Pmn21 or P21nm, a = 15.337(3), b = 17.051(3), c = 6.931(2)Å, Z = 4, dcalc. = 4.19 g/cm3 and dmeas. 4.10 g/cm3. The strongest lines in the X-ray powder pattern are [d(Å),hkl] 8.55(100) 020, 6.94(50) 210, 4.11(60) 301, 3.723(60) 321, 3.460(50) 002 and 2.772(70) 511. The average of four electron-microprobe analyses gave: CaO 4.15%, UO3 76.14%, CO2 (by chromatography) 14.80% and H2O (by difference) 4.91%. Empirical formula Ca0.85(UO2)3.08(CO3)3.89.3.15H2O or ideally Ca(UO2)3(CO3)4.3H2O. Fontanite was found in the uranium deposit of Rabejac (7 km SSE of Lodève, Hérault, France) excaved in the Saxonian pelitic rocks of the Permian basin of Lodève. The mineral appears in the alteration zone together with billietite and uranophane. The name honours Dr. François Fontan, mineralogist at the University of Toulouse.
Keywords
new mineral • fontanite • uranyl carbonate • Lodeve • France