Uranopolycrase, with chemical formula (U0.62Y0.29Th0.07Nd0.01Ca0.02Mn0.03)(Sigma=1.04)(Ti1.46Nb0.36Ta0.12)(Sigma=1.94)O-6 (ideally (U,Y)(Ti,Nb,Ta)(2)O-6), 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), b = 5.558(5), c = 5.173(4) Å. The strongest lines in the X-ray powder pattern are: 2.99 Angstrom, 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.
Uranopolycrase, the uranium-dominant analogue of polycrase-(Y), a new mineral from Elba Island, Italy, and its crystal structure
ORLANDI, PAOLO;PASERO, MARCO;PERCHIAZZI, NATALE
1993-01-01
Abstract
Uranopolycrase, with chemical formula (U0.62Y0.29Th0.07Nd0.01Ca0.02Mn0.03)(Sigma=1.04)(Ti1.46Nb0.36Ta0.12)(Sigma=1.94)O-6 (ideally (U,Y)(Ti,Nb,Ta)(2)O-6), 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), b = 5.558(5), c = 5.173(4) Å. The strongest lines in the X-ray powder pattern are: 2.99 Angstrom, 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.I documenti in IRIS sono protetti da copyright e tutti i diritti sono riservati, salvo diversa indicazione.
