DOI

A new mineral species zincovelesite-6N6S with the simplified formula Zn 3(Fe 3+,Mn 3+,Al,Ti) 8O 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-6N6S 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-6N6S 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-6N6S 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 2O determined by gas chromatography of ignition products): MgO 0.97, CuO 0.50, ZnO 30.80, Al 2O 3 8.17, Mn 2O 3 21.31, Fe 2O 3 29.44, TiO 2 5.28, Sb 2O 5 3.74, H 2O 1.1, total 101.31. The empirical formula based on 16 O atoms is H 1.05Zn 3.26Mg 0.21Cu 0.05Fe 3+ 3.18Mn 3+ 2.32Al 1.38Ti 0.57Sb 0.20O 16. Zincovelesite-6N6S is trigonal, probable space group P-3m1, 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-6N6S 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 discovery locality near the city of Veles.

Язык оригиналаАнглийский
Страницы (с-по)733-742
Число страниц10
ЖурналMineralogy and Petrology
Том112
Номер выпуска5
DOI
СостояниеОпубликовано - 1 окт 2018

    Предметные области Scopus

  • Геофизика
  • Геохимия и петрология

ID: 34864457