Deliens, M.
Piret, Paul
[UCL]
Fontanite from Rabejac occurs as elongated rectangular lath-shaped crystals. Bright yellow and transparent with a vitreous luster. Light green fluorescence under long-wave UV light. Optically 2V(-) with alpha = 1.603 (calc.), beta = 1.690; gamma = 1.710, 2V(meas.) = 49-degrees. Optical orientation: X = b, Y = a and Z = c. System orthorhombic, space group Pmnm, Pmn2(1) or P2(1)nm, a = 15.337(3), b = 17.051(3), c = 6.931(2)angstrom, Z = 4, d(calc.) = 4.19 g/cm3 and d(meas.) 4.10 g/cm3. The strongest lines in the X-ray powder pattern are [d(angstrom),I,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 Lodeve, Herault, France) excaved in the Saxonian pelitic rocks of the Permian basin of Lodeve. The mineral appears in the alteration zone together with billietite and uranophane. The name honours Dr. Francois Fontan, mineralogist at the University of Toulouse.
Bibliographic reference |
Deliens, M. ; Piret, Paul. Fontanite, Hydrated Uranyle and Calcium-carbonate, a New Mineral Species From Rabejac, Herault, France. In: European Journal of Mineralogy : an international journal of mineralogy, geochemistry and related sciences, Vol. 4, no. 6, p. 1271-1274 (1992) |
Permanent URL |
http://hdl.handle.net/2078.1/50114 |