Publication Date:
1983-03-01
Description:
Eluvial pebbles from the Afu Hills, Nigeria, are largely composed of fluocerite, Ce0.50La0.28Nd0.11 Pr0.04Th0.03Ca0.02F3, with minor monazite. The fluocerite shows two types of alteration, to bastnäsite, and to bastnäsite-(La) with cerianite. Electron microprobe analyses are given for fluocerite, monazite, bastnäsite and bastnäsite-(La). The refined cell parameters of the fluocerite are a = 7.130±0.001, c = 7.2985 ± 0.001 Å. Strongest lines are 3.204 Å (100), 3.65 (45), 2.059 (45), 2.010 (45) and 3.565 (40). Space group P 63/mcm, Z = 6, Dcalc. = 6.12 g cm−3, ω = 1.613, ε = 1.609 both ±0.002, uniaxial negative. For bastnäsite a = 7.131 ± 0.002, c = 9.786±0.004 Å, for cerianite a = 5.460 ± 0.005 Å.
Print ISSN:
0026-461X
Electronic ISSN:
1471-8022
Topics:
Geosciences
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