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Paratooite-(La), a new lanthanum-dominant rare-earth copper carbonate from Paratoo, South Australia

A. Pring^1,2,3,*, K. Wallwork^3,, J. Brugger^1,2 and U. Kolitsch⁴

¹ Department of Mineralogy, South Australian Museum, North Terrace, Adelaide, S.A. 5000, Australia
² Department of Geology and Geophysics, University of Adelaide, North Terrace, Adelaide, S.A. 5000, Australia
³ School of Chemistry, Physics and Earth Sciences, The Flinders University of South Australia, GPO Box 2100 Adelaide, South Australia 500, Australia
⁴ Institut für Mineralogie und Kristallographie, Universität Wien, Geozentrum, Althanstr. 14, A-1090 Vienna, Austria

^* E-mail: pring.allan{at}saugov.sa.gov.au

Paratooite-(La) is a new lanthanum-dominant rare-earth copper carbonate from the Paratoo copper mine, near Yunta, Olary district, South Australia. Paratooite-(La) occurs as sheaves and radiating sprays of blade-like to tabular pale blue crystals in thin fissures in a slaty country rock. Individual crystals are typically 50–200 µm in maximum dimension but <5 µm thick. Associated minerals include donnayite-(Y), kamphaugite-(Y), and bastnäsite-(La). Electron microprobe and CHN analyses gave: La₂O₃ 26.47; Pr₂O₃ 7.74; Nd₂O₃ 8.15; Sm₂O₃ 0.66; Gd₂O₃ 0.85; Y₂O₃ 0.72; CaO 7.57; SrO 3.15; Na₂O 3.3; CuO 5.77; F 0.24; CO₂ 32.05; NO₂ 1.12; –O=F –0.10; sum 100.03, yielding an empirical formula of (La_3.54Ca_2.94Na_2.32Nd_1.05Pr_1.03Sr_0.66Y_0.14Gd_0.10Sm_0.0.8)_11.86Cu_1.58(C_15.84N_0.53)O_47.76F_0.24. The simplified formula is (REE,Ca,Na,Sr)₆Cu(CO₃)₈ or possibly REE₃(Ca,Sr)₂NaCu(CO₃)₈. The mineral is pale turquoise-blue to pale blue in colour, transparent, with a pearly to vitreous lustre and a pale blue streak. No cleavage was observed but the morphology and TEM studies indicate a cleavage parallel to {100}. The Mohs hardness is estimated to be 4. The strongest lines in the X-ray powder pattern are [d_obs (I_obs) (hkl)]: 5.047 (53) (200); 4.786 (49) (021); 3.957 (43) (220); 3.468 (43) (012, 221); 2.927 (100) (202); 2.530 (52) (241); 2.344 (22) (420,103); 2.232 (20) (421). A synchrotron powder diffraction pattern was indexed on a primitive orthorhombic cell with a = 10.0862(5), b = 12.8088(6), c = 7.2360(4) Å, V = 934.8(1) ų and Z = 2. The crystal structure of the new mineral could not be determined but powder diffraction data indicate the space group is probably P222, Pmmm, P222₁ or Pmm2. The measured density is 3.68(3) g/cm³ and the calculated density is 3.78 g/cm³. Paratooite-(La) is biaxial negative with = 1.605(3), ß = 1.696(3) and = 1.752(2); pleochroism is medium strong; X very pale bluish, Y and Z bluish (with greenish tint) with absorption Z Y >> X. Paratooite-(La) is a supergene mineral which precipitated from mildly basic carbonated groundwaters. The mineral is named for the type locality.

KEYWORDS: paratooite-(La), new mineral, rare-earth carbonates, Paratoo deposit, South Australia

This article has been cited by other articles:

				J. Brugger, J. Ogierman, A. Pring, H. Waldron, and U. Kolitsch Origin of the secondary REE-minerals at the Paratoo copper deposit near Yunta, South Australia Mineralogical Magazine, December 1, 2006; 70(6): 609 - 627. [Abstract] [Full Text] [PDF]