Romeite

Abstract: The legacy of copper (Cu) mining at Spania Dolina-Piesky and Ľubietova-Svatodusna (central Slovakia) is waste rock and soil, surface waters, and groundwaters contaminated with antimony (Sb), arsenic (As), Cu, and other metals. Copper ore is hosted in chalcopyrite (CuFeS 2 ) and sulfosalt solid-solution tetrahedrite-tennantite {Cu 6 [Cu 4 (Fe,Zn) 2 ]Sb 4 S 13 –Cu 6 [Cu 4 (Fe,Zn) 2 ]As 4 S 13 } that show wide-spread oxidation characteristic by olive-green color secondary minerals. Tetrahedrite-tennantite can be a significant source of As and Sb contamination. Synchrotron-based μ-XRD, μ-XRF, and μ-XANES combined with electron microprobe analyses have been used to determine the mineralogy, chemical composition, element distribution, and Sb speciation in tetrahedrite-tennantite oxidation products in waste rock. Our results show that the mobility of Sb is limited by the formation of oxidation products such as tripuhyite and romeite group mineral containing 36.54 wt% Sb for samples where the primary mineral chemical composition is close to tetrahedrite end-member. Antimony K -edge μ-XANES spectra of these oxidation products indicate that the predominant Sb oxidation state is 5 + . Arsenic and Cu are also hosted by amorphous phases containing 6.23 wt% Sb on average and these are intergrown with tripuhyite and romeite. Antimony in this environment is not very mobile, meaning it is not easily released from solid phases to water, especially compared to As, Cu, and S. For samples where the primary sulfosalt is close to tennantite composition, the oxidation products associated with tennantite relicts contain 2.43 wt% Sb and are amorphous. The variable solubility of the secondary minerals that have been identified is expected to influence mobility of Sb and As in near-surface environment.

Abstract: A new mineral ferricoronadite with the simplified formula Pb(Mn6 4+Fe2 3+)O16 was discovered in the orogenetic zone related to the “Mixed Series” metamorphic complex near the Nežilovo village, Pelagonian massif, Republic of Macedonia. Associated minerals are franklinite, gahnite, hetaerolite, romeite, almeidaite, Mn-analogue of plumboferrite, zincohogbomite analogue with Fe3+ > Al, zincochromite, Zn-bearing talc, Zn-bearing muscovite, baryte, quartz and zircon. Ferricoronadite is a late hydrothermal mineral forming veinlets up to 8 mm thick in granular aggregate predominantly composed by zinc-dominant spinels. The new mineral is opaque, black, with brownish black streak. The luster is strong submetallic to metallic. The micro-indentation hardness is 819 kg/mm2. Distinct cleavage is observed on (100). Ferricoronadite is brittle, with uneven fracture. The density calculated from the empirical formula is 5.538 g/cm3. In reflected light, ferricoronadite is light gray. The reflectance values [R max/R min, % (λ, nm)] are: 28.7/27.8 (470), 27.6/26.6 (546), 27.2/26.1 (589), 26.5/25.5 (650). The IR spectrum shows the absence of H2O and OH groups. According to the Mossbauer spectrum, all iron is trivalent. The Mn K-edge XANES spectroscopy shows that Mn is predominantly tetravalent, with subordinate Mn3+. The chemical composition is (wt%; electron microprobe, Mn apportioned between MnO2 and Mn2O3 based on the charge-balance requirement): BaO 5.16, PbO 24.50, ZnO 0.33, Al2O3 0.50, Mn2O3 9.90, Fe2O3 11.45, TiO2 4.19, MnO2 44.81, total 100.84. The empirical formula based on 8 cations Mn + Fe + Ti + Al + Zn pfu is Pb1.03Ba0.32(Mn 4.85 4+ Fe 1.35 3+ Mn 1.18 3+ Ti0.49Al0.09Zn0.04)Σ8.00O16. The crystal structure was determined using single-crystal X-ray diffraction data. The new mineral is tetragonal, space group I4/m, a = 9.9043(7), c = 2.8986(9) A, V = 284.34(9) A3, Z = 1. In ferricoronadite, double chains of edge-sharing (Mn, Fe, Ti)-centered octahedra are connected via common vertices to form a pseudo-framework with tunnels containing large cations Pb and Ba. The strongest lines of the powder X-ray diffraction pattern [d, A (I, %) (hkl)] are: 3.497 (33) (220), 3.128 (100) (−130, 130), 2.424 (27) (−121, 121), 2.214 (23) (240, −240), 2.178 (17) (031), 1.850 (15) (141, −141), 1.651 (16) (060), 1.554 (18) (−251, 251). Ferricoronadite is named as an analogue of coronadite Pb(Mn6 4+Mn2 3+)O16 with the major charge-compensating octahedral cation Fe3+ instead of Mn3+.

Abstract: The chemical composition of romeite from the regionally metamorphosed bedded manganese ore deposit of the Gozaisho mine, Fukushima Prefecture, is (Na1.00Ca0.80Mn0.01)Σ1.81Sb2 [O5.69F0.89(OH)0.36]Σ6.94, calculated on the basis of Sb=2. It occurs as honey yellow to brownish yellow octahedra up to 4 mm long in braunite-rhodonite ore. It is cubic, Fd3m, a=10.265(2) A, Z=8. Microbalance measured specific gravity is close to the calculated density 5.096 g/cm3. The single crystal study using the four-circle diffractometer confirms the isostructural relation to pyrochlore and stibiconite group minerals, yielding R=1.3%; Rw=1.8%. The precise ideal formula of romeite is to be simply NaCaSb2O6(F, OH). The quantitative relation of Na to Ca is similar to the case of pyrochlore series minerals where Ca≥Na.