Publication details
Luboržákite, Mn2AsSbS5, a new member of pavonite homologous series from Vorontsovskoe gold deposit, Northern Urals, Russia
| Authors | |
|---|---|
| Year of publication | 2020 |
| Type | Article in Periodical |
| Magazine / Source | Mineralogical Magazine |
| MU Faculty or unit | |
| Citation | |
| Web | https://doi.org/10.1180/mgm.2020.48 |
| Doi | http://dx.doi.org/10.1180/mgm.2020.48 |
| Keywords | luborzakite; Mn2AsSbS5; new mineral; chemical composition; crystal structure; pavonite homologous series; Vorontsovskoe deposit; Northern Urals |
| Description | Luborzakite, ideally Mn2AsSbS5, is a new mineral from the Vorontsovskoe gold deposit, Northern Urals, Russia It forms long-prismatic crystals up to 70 x 20 mu m and anhedral grains of the same size embedded in the matrix of Mn-bearing dolomite and Mn-bearing calcite. Associated minerals include pyrite, orpiment, realgar, stibnite, aktashite, alabandite, boscardinite, chabourneite, coloradoite, clerite, ecrinsite, gold, routhierite, sphalerite and twinnite. Lubor'Zakite is black, opaque with metallic lustre and has a black streak. It is brittle and has an uneven fracture. No cleavage and parting have been observed. Mohs hardness is 4-41/2. D-calc = 4.181 g cm(-3). In reflected light, luboriakite is tin-white, weakly anisotropic with rotation tints varying from dark grey to grey. The chemical composition of luboriakite is (wt.%; electron microprobe, WDS mode): Mn 21.23, Cu 0.29, Ag 0.56, Pb 1.90, As 15.25, Sb 27.03, S 33.23, total 99.49. The empirical formula based on the sum of all atoms = 9 apfu is Mn1.86Pb0.04Ag0.03Cu0.02As0.98Sb1.07S5.00. The new mineral is monoclinic, space group C2/m with a = 12.5077(6), b = 3.8034(2), c = 16.0517(8) angstrom, beta = 94.190(4)degrees, V= 761.57(6) angstrom(3) and Z = 4. The crystal structure of luboriakite was solved from the single-crystal X-ray diffraction data to R = 0.0383 for 712 observed reflections with I> 3 sigma(I). Luboriakite is a new member of the heterochemical isostructural series of `unit-cell twinned' structures, named the pavonite series. The new mineral honours Lubor Zak, a prominent Czech crystallographer and the professor of the Charles University in Prague, Czech Republic. |