Affiliation:
1. Fersman Mineralogical Museum RAS
2. Moscow State University
3. Saint Petersburg State University
4. Masaryk University
5. University of Padova
6. Federal Research Center of Problems of Chemical Physics and Medicinal Chemistry RAS
Abstract
Lednevite, ideally Cu[PO3(OH)]·H2O, is a new mineral discovered at the 255 m level of the Murzinskoe Au deposit, Krasnoshchyokovskiy District, Altai Krai, Western Siberia, Russia. It forms spherulites up to 0.1 mm in diameter, composed of very thin fibers and grouped in aggregates up to 1.5 mm across. Lednevite overgrows philipsburgite crystals on a matrix of epidote-andradite skarn and quartz and associates with malachite, chrysocolla, kaolinite, goethite and P-bearing cornubite. The new mineral is transparent, has sky blue color, very pale blue streak and vitreous lustre. Cleavage is not observed. The Mohs’ hardness is ~3. Dmeas = 3.18(2) g cm–3, Dcalc = 3.196 g cm–3. The chemical composition of lednevite is (electron microprobe, wt.%; H2O by stoichiometry): CuO 40.20, ZnO 3.92, P2O5 36.29, As2O5 4.80, H2O 14.98, total 100.15. The empirical formula calculated on the basis of 3 H and 5 O apfu is (Cu0.91Zn0.09)Σ1.00[(P0.92As0.08)Σ1.00O3(OH)]·H2O. The crystal structure was refined by the Rietveld method to Rp = 0.0042, Rwp = 0.0061, Robs = 0.0354. Lednevite is monoclinic, space group P21/a, with a = 8.6459(6), b = 6.3951(4), c = 6.8210(5) A, β = 93.866(2)°, V = 376.28(4) A3 and Z = 4. The strongest lines of the powder X-ray diffraction pattern [d, A (I, %) (hkl)] are: 5.135 (100) (110), 4.648 (33) (011), 3.241 (28) (21-1), 3.095 (49) (211), 2.891 (27) (11-2), 2.775 (53) (112), 2.568 (29) (220). The new mineral is isotypic to the synthetic CuHPO4·H2O. Some optical and spectroscopic data, which could not be obtained on natural sample, were obtained from the synthesized material. The crystal structure of the synthetic analogue of lednevite was solved from single-crystal X-ray diffraction data and refined to R1 = 0.0173 for 1159 independent reflections with I 2σ(I). All positions of H atoms were determined. Lednevite is named for Vladimir Sergeevich Lednev, amateur mineralogist from Barnaul (Altai Krai) who collected the sample with the new mineral.
Publisher
The Russian Academy of Sciences
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