Yttriaite-(Y): the natural occurrence of Y2O3 from the Bol'shaya Pol'ya River, Subpolar Urals Russia  

Stuart J. Mills
Department of Earth and Ocean Sciences University of British Columbia
Vancouver, British Columbia, Canada V6T 1Z4

Pavel M. Kartashov
Institute of Geology Ore Deposits
Petrography, Mineralogy and Geochemistry (IGEM) of Russian Academy of Sciences Staromonetnyi pereulok 35, 109017 Moscow, Russia,

Chi Ma, George R. Rossman 
Division of Geological and Planetary Sciences
California Institute of Technology, Pasadena, California 91125, USA

Margarita I. Novgorodova
Fersman Mineralogical Museum,
Leninskiy Prospekt 18(2), Moscow 117071, Russia
 
Anthony R. Kampf
Mineral Sciences Department, Natural History Museum of Los Angeles County, 900 Exposition Boulevard, Los Angeles, California 90007, USA


Mati Raudsepp
Department of Earth and Ocean Sciences
University of British Columbia, Vancouver, British Columbia, Canada 
 

  Abstract

 Yttriaite-(Y), ideally Y2O3, is a new mineral (IMA2010–039) from the alluvial deposits of the Bol'shaya Pol'ya river, Subpolar Urals, Russia. The new mineral occurs as isolated crystals, typically cubo-octahedra less than 6 μm in size, embedded in massive native tungsten. Associated minerals include: copper, zircon, osmium, gold and pyrite. The main forms observed are {100} and {111}. Due to the crystal size, physical properties could not be determined; however, the properties of synthetic Y2O3 are well known. Synthetic Y2O3 crystals are colourless to white with a white streak; crystals are transparent with an adamantine luster, whilst massive Y2O3 is typically translucent with an earthy luster. Synthetic Y2O3 has a Vickers hardness of 653.91, which corresponds to 5.5 on the Mohs scale. Synthetic Y2O3 crystals have good cleavage on {111}. Yttriaite-(Y) is isotropic; the refractive index measured at 587 nm on synthetic Y2O3 is n = 1.931. The empirical chemical formula (mean of 4 electron microprobe analyses) calculated on the basis of 3 O is: Y1.98Dy0.01Yb0.01O3. Yttriaite-(Y) is cubic, space group Ia-3, with parameters a = 10.6018(7) , V = 1191.62(7) 3 and Z = 16. The five strongest lines in the powder X-ray diffraction pattern (measured on synthetic Y2O3 using synchrotron radiation) are [dobs in (I) (hkl)]: 3.0646 (100) (222), 1.8746 (55) (440), 1.5984 (38) (622), 2.6537 (26) (400) and 4.3356 (14) (211). The mineral named is based on the common name for the chemical compound, yttria.

yttriaite

Yttriaite-(Y) crystals (false yellow color) included in tungsten metal from the Bol'shaya Pol'ya river occurrence.