Decrespignyite-(Y), a new copper yttrium rare earth carbonate chloride hydrate from Paratoo, South Australia
- Author(s)
- K Wallwork, Uwe Kolitsch, Allan Pring, Lutz Nasdala
- Abstract
Decrespignyite-(Y) is a new copper yttrium rare earth carbonate chloride hydrate from the Paratoo copper mine, near Yunta, Olary district, South Australia. Decrespignyite-(Y) occurs as blue crusts,coatings and fillings in thin fissures on the slatey country rock. Individual pseudohexagonal platelets are typically 10-50 μm in maximum dimension and are often curved. Associated minerals include caysichite-(Y), donnayite-(Y), malachite and kamphaugite-(Y). Electron microprobe and CHN analyses gave: Y2O3 42.2; La2O3 0.1; Pr2O3 0.1; Nd2O3 1.3; Sm2O3 1.0; Gd2O3 4; Tb2O3 0.4; Dy2O3 3.7; Ho2O3 2.6; Er2O3 2.5; CaO 0.5; CuO 10.9; Cl 3.0; CO2 19.8; H2O 10.8, yielding an empirical formula of No cleavage was observed but the morphology suggests that cleavage would be on {010}. The Mohs' hardness is estimated to be 4. The strongest lines in the X-ray powder pattern are [dobs (Iobs) (hkl)] 22.79 (30) (010); 7.463 (30) (001); 7.086 (50) (011); 6.241 (100) (021); 4.216 (30) (Ī 12); 3.530 (40) (022); 3.336 (30) (032); 2.143 (30) (222, 401). The powder diffraction pattern was indexed on a monoclinic cell with a = 8.899(6), b = 22.77(2), c = 8.589(6) Å, β = 120.06(5)°, V = 1506.3(7) Å3 and Z = 4. The structure of the new mineral could not be determined but powder diffraction data indicate the space group is P2, Pm or P2/m. The measured density is 3.64(2) g/cm3 and the calculated density is 3.645 g/cm3. Decrespignyite-(Y) is biaxial negative with α = 1.604(4) and γ = 1.638(3) with β very close to γ; pleochroism is medium strong; X very pale bluish, Y and Z bluish (with greenish tint). Decrespignyite-(Y) is a supergene mineral which precipitated from mildly basic carbonated ground waters. The mineral is named after Robert Champion de Crespigny, a prominent figure in the Australian mining industry and chancellor of the University of Adelaide.
- Organisation(s)
- Department of Mineralogy and Crystallography
- External organisation(s)
- Flinders University, Johannes Gutenberg-Universität Mainz
- Journal
- Mineralogical Magazine
- Volume
- 66
- Pages
- 181-188
- No. of pages
- 8
- ISSN
- 0026-461X
- DOI
- https://doi.org/10.1180/0026461026610021
- Publication date
- 2002
- Peer reviewed
- Yes
- Austrian Fields of Science 2012
- 1051 Geology, Mineralogy
- Portal url
- https://ucrisportal.univie.ac.at/en/publications/5a080458-9960-4ac9-89f0-b878f9f2f773