Zincovelesite-6N6S, Zn3(Fe3+,Mn3+,Al,Ti)8O15(OH), a new högbomite-supergroup mineral from Jacupica mountains, Republic of Macedonia

• Published in: Mineralogy and petrology 2018-10, Vol.112 (5), p.733-742
• Main Authors: Chukanov, Nikita V., Krzhizhanovskaya, Maria G., Jančev, Simeon, Pekov, Igor V., Varlamov, Dmitry A., Göttlicher, Jörg, Rusakov, Vyacheslav S., Polekhovsky, Yury S., Chervonnyi, Alexandr D., Ermolaeva, Vera N.
• Format: Article
• Language: English
• Subjects: Aluminum oxide; Analytical methods; Composition; Diffraction; Diffraction patterns; Dolomite; Dolostone; Earth and Environmental Science; Earth Sciences; Electron microprobe; Fluorapatite; Gas chromatography; Geochemistry; Hardness; Hematite; Indentation; Inorganic Chemistry; Iron; Iron oxides; Luster; Manganese; Manganese oxides; Mineralogy; Mountains; Original Paper; Platelets; Reflectance; Scheelite; Silicates; Spectroscopy; Spectrum analysis; Talc; Titanium; Titanium dioxide; Water hardness; X ray powder diffraction; X-ray diffraction; X-rays; Zinc; Zinc oxide; Zircon
• ISSN: 0930-0708; 1438-1168
• DOI: 10.1007/s00710-018-0555-1

A new mineral species zincovelesite-6 N 6 S with the simplified formula Zn 3 (Fe 3+ ,Mn 3+ ,Al,Ti) 8 O 15 (OH) was discovered in the orogenetic zone related to the “Mixed Series” metamorphic complex near the Nežilovo village, Jacupica Mountains, Pelagonia mountain range, Republic of Macedonia. In oxide Zn-Fe-Mn ore, zincovelesite-6N6S forms lenticular aggregates up to 2 × 2 × 0.5 mm consisting of thin near-coplanar platelets up to 70 × 70 × 1 µm 3 and associated with franklinite, gahnite, hetaerolite, zincochromite, ferricoronadite, baryte, As-rich fluorapatite, dolomite, Zn-bearing talc, almeidaite, hydroxycalcioroméite, zircon, quartz, and scheelite. In silicate-baryte zones of the metasomatic rock, uniaxial intergrowths of zincovelesite-6 N 6 S with nežilovite are observed. The new mineral is opaque, black, with brownish-black streak. The lustre is strong submetallic to metallic. The micro-indentation hardness is 1118 kg/mm 2 which corresponds to Mohs’ hardness ca . 6½. Zincovelesite-6 N 6 S is brittle, with uneven fracture. No cleavage or parting is observed. The density calculated from the empirical formula is 5.158 g/cm 3 . In reflected light zincovelesite-6 N 6 S is light grey. The reflectance values [ R max / R min , % (λ, nm)] are: 17.1/13.4 (470), 16.5/12.8 (546), 16.2/12.6 (589), 15.6/12.2 (650). The IR spectrum shows the presence of OH groups. According to the Mössbauer spectrum, all iron is trivalent. The Mn K -edge XANES spectroscopy shows that Mn is predominantly or completely trivalent. The average chemical composition is (wt%; electron microprobe, H 2 O determined by gas chromatography of ignition products): MgO 0.97, CuO 0.50, ZnO 30.80, Al 2 O 3 8.17, Mn 2 O 3 21.31, Fe 2 O 3 29.44, TiO 2 5.28, Sb 2 O 5 3.74, H 2 O 1.1, total 101.31. The empirical formula based on 16 O atoms is H 1.05 Zn 3.26 Mg 0.21 Cu 0.05 Fe 3+ 3.18 Mn 3+ 2.32 Al 1.38 Ti 0.57 Sb 0.20 O 16 . Zincovelesite-6 N 6 S is trigonal, probable space group P -3 m 1, a  = 5.902(2) Å, c  = 55.86(1) Å, V  = 1684.8(9) Å 3 , Z  = 6. The strongest lines of the powder X-ray diffraction pattern [ d , Å (I, %) ( hkl )] are: 2.952 (62) (110), 2.881 (61) (1.0.16), 2.515 (100) (204), 2.493 (88) (1.1.12), 2.451 (39) (1.0.20), 1.690 (19) (304, 2.1.16), 1.572 (19) (2.0.28), 1.475 (29) (221). Zincovelesite-6 N 6 S is the first Fe 3+ -dominant member of the högbomite supergroup and, thus, can be considered as a parent species of a new mineral group. The rootname velesite is given for the discove