Original paper

La trimounsite-(Y), nouveau silicotitanate de terres rares de Trimouns, Ariège, France: (TR)2Ti2SiO9

Piret, Paul; Deliens, Michel; Pinet, Michèle

European Journal of Mineralogy Volume 2 Number 5 (1990), p. 725 - 730

8 references

published: Oct 4, 1990
manuscript accepted: Mar 29, 1990
manuscript received: Dec 6, 1989

DOI: 10.1127/ejm/2/5/0725

BibTeX file

ArtNo. ESP147050205013, Price: 29.00 €

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Abstract

Abstract Trimounsite-(Y) occurs as light brown prisms in dolomitic levels of the Trimouns talc deposit, Ariège, France. The crystals elongated along [001] are transparent to translucent with an adamantine lustre. The Mohs hardness is 7. Optically biaxial negative with α, ß and γ > 2.10. Monoclinic, F21/c with a = 12.299(2), b = 11.120(2), c = 4.858(1) Å, ß = 95.62°(1), dmeas.=5.0 g/cm3, dcalc. = 4.85 g/cm3 and Z = 4. Strongest lines in the X-ray powder pattern [d(Å),(I),hkl] are: 2.82 (10) 321̅, 3.44 (9) 211 and 121, 1.959 (6) 312 and 350, 1.643 (6) 550,640 and 602̅, 2.117 (5) 341̅. Electron microprobe analyses give: SiO2 11.8, TiO2 34.5, Y2O3 34.6, Sm2O3 0.4, Gd2O3 1.9, Tb2O3 0.7, Dy2O3 5.7, Ho2O3 0.8, Er2O3 5.0 and Yb2O3 4.8, total 100.2 %. Formula (REE)2Ti2SiO9. Main associated minerals are allanite and bastnaesite. The name refers to the locality.

Keywords

new mineraltrimounsite-(Y)silicotitanaterare earthsTrimounsFrance