Original paper

Uranopolycrase, the uranium-dominant analogue of polycrase-(Y), a new mineral from Elba Island, Italy, and its crystal structure

Aurisicchio, Carlo; Orlandi, Paolo; Pasero, Marco; Perchiazzi, Natale

European Journal of Mineralogy Volume 5 Number 6 (1993), p. 1161 - 1166

9 references

published: Dec 1, 1993
manuscript accepted: Jul 19, 1993
manuscript received: Mar 16, 1993

DOI: 10.1127/ejm/5/6/1161

BibTeX file

ArtNo. ESP147050506009, Price: 29.00 €

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Abstract

Abstract Uranopolycrase, with chemical formula (U0.62Y0.29Th0.07Nd0.01Ca0.02Mn0.03)Σ=1.04 (Ti1.46Nb0.30Ta0.12)Σ=1.94O6 (ideally (U,Y)(Ti,Nb,Ta)2O6), was found in the "Fonte del Prete" pegmatitic vein, near S. Piero in Campo village, Elba Island, Tuscany, Italy. It occurs as tabular {100} crystals, elongated in the [001] direction. The mineral is opaque, with brown-red color and adamantine luster, mean VHN20 = 659. In reflected light, color is pale grey with bluish tones; pleochroism, anisotropism and bireflectance were not observed. Reflectance values, measured in air, range from 21.5% to 25.1%. Uranopolycrase is orthorhombic, space group Pbcn, with a = 14.51(1) A, b - 5.558(5), c = 5.173(4). The strongest lines in the X-ray powder pattern are: 2.99 Å, 1.90, 1.48, 1.77, 2.78. The structure of uranopolycrase has been refined up to R = 0.047 with single-crystal X-ray diffraction data. The relationships of uranopolycrase with other natural and synthetic compounds with the same structural topology are briefly discussed.

Keywords

uranopolycrasenew mineraleuxenite groupcrystal structureElba IslandItaly