Petrochemical Features of Manganese Nodules in Madaka (Sheet 142) SE and Part of Kwana - Bala (Sheet 142) NE, Nigeria

Manganese nodule occurs in Madaka (Sheet 142) SE and part of Kwana - Bala (Sheet 142) NE, Nigeria. Four (4) samples of manganese nodules were analyzed petrochemical using X-ray diffractometry (XRD), reflected light microscopy, Electron probe micro analysis (EPMA), Atomic absorption spectrophotometer (AAS). XRD reveals sphalerite, manganates and ilmenite as major minerals in the nodules. Accessory minerals are siderite and rutile. Chemical study of the manganese nodules from Madaka and Kwana - Bala reveals that Mn-, Fe-, Co-, Ni-, and Cu-, minerals (including native elements and sulfides) commonly occur in the samples. Also, the results indicate that increased in Mn relative to the manganite content (10AO- plus 7AO), led to increase in Ni and Cu recovery. However, slightly greater amounts by weight of Ni and Cu were dissolved from the manganites than from Mn. This followed from the much higher Ni and Cu contents of manganites relative to Mn. The exploration for Ni and Cu from nodules on assay criterion was inadequate; the sphalerite Mn02 phase structure would also be a necessary criterion. It was suggested that nodules could be processed upon beneficiation for Ni and Cu contents for a future time relative to the original processing. It was thus proposed that Ni and Cu could be produced from manganese nodules in the study area.

Sulfate mineralization in a tunnel of the Pyatigorsky proval cave, North Caucasus

The paper reports on the results of studies of supergene sulfate mineralization found in a tunnel of the Pyatigorskiy Proval cave. The sulfate minerals include humberstonite K3Na7Mg2(SO4)6(NO3)2·6H2O, sid-eronatrite Na2Fe(SO4)2(OH)·3H2O, metasideronatrite Na2Fe(SO4)2(OH)·H2O, natrojarosite NaFe3(SO4)2(OH)6, tamarugite NaAl(SO4)2·6H2O, and epsomite MgSO4·7H2O, which were identifed by electron probe micro-analysis, powder X-ray difraction and infrared spectroscopy. The presence sulfate sulfur can be related to both the oxidation of sulfde grains, which were found in some samples, and the oxidation of gaseous H2S air oxygen. Humberstonite and metasideronatrite are found for the frst time in Russia.

Crystal Chemistry of Zemannite-Type Structures: III. Keystoneite, the Ni2+-Analogue of Zemannite, and Ferrotellurite Discredited

ABSTRACT Keystoneite (IMA87–049) is a tellurite mineral from the Keystone mine, Magnolia District, Boulder County, Colorado, USA. In this paper the first full description of keystoneite is presented. Keystoneite is the Ni2+ analogue of zemannite and has the ideal zemannite-like formula of Mg0.5Ni2+Fe3+(Te4+O3)3·4H2O. The chemical composition via electron-probe micro-analysis (in wt.%; standard deviations in brackets) is Na2O 0.3 (0.2), K2O 0.1 (0.0), MgO 4.3 (0.3), Mn2O3 1.1 (0.7), Fe2O3 5.1 (1.2), NiO 12.7 (1.7), and TeO2 65.5 (0.7). H2O was determined by TGA analysis, giving 15(3) wt.% H2O, however, H2O from the structural determination gave 10.0 wt.%, the latter giving an analytical total of 99.1 wt.%. Keystoneite crystallizes in the non-centrosymmetric space group P63. The six strongest observed powder-diffraction lines [d,Å(I)(hkl)] are 8.12(90)(100), 4.05(80)(200), 2.952(50)(112), 2.838(50)(121,211), 2.774(100)(202), and 1.720(60)(204). The unit-cell parameters determined from single-crystal X-ray diffraction are a = 9.3667(5) Å, c = 7.6173(3) Å, V = 578.77(6) Å3, and Z = 2. Keystoneite was first identified from a specimen of “ferrotellurite”, a mineral with the reported formula Fe2+Te6+O4. The discreditation of “ferrotellurite” has been accepted by the IMA-CNMNC, Proposal 19-G, as no material corresponding to a phase remotely similar to Fe2+Te6+O4 was found on any historical samples labelled as containing “ferrotellurite”.

Garnet Characteristics Associated with Jiama Porphyry-Skarn Cu Deposit 1# Skarn Orebody, Tibet, Using Thermal Infrared Spectroscopy

Field measurements of the thermal infrared (TIR) reflectance from drill hole samples proved to be an effective method to map variations in garnet species associated with hydrothermal alteration zonation of the Jiama porphyry-skarn Cu deposit 1# skarn orebody, Tibetan Plateau, China. The TIR mineral spectral information was combined with electron probe micro-analysis (EPMA) measurements to provide geological insights on effectively determining (a) garnet end components and providing a format for further research on the type and genesis of the deposit; (b) the significance of the characteristic spectrum of garnet to the variation of mineralization environment; (c) the relationship between the characteristic spectrum of garnet and Fe/Al content; (d) the garnet characteristic spectrum to the economic mineralization. The results suggest that garnet characteristics of the thermal infrared spectrum can be used as an indicator for skarn deposit prospecting.

Indium and Antimony Distribution in a Sphalerite from the “Burgstaetter Gangzug” of the Upper Harz Mountains Pb-Zn Mineralization

The sphalerite from the Burgstaetter Gangzug, a vein system of the Upper Harz Mountain nearby the town of Clausthal-Zellerfeld, exhibits a very interesting and partly complementary incorporation pattern of Cu, In and Sb, which has not yet been reported for natural sphalerite. A sphalerite specimen was characterized with electron probe micro-analysis (EPMA) and atom probe tomography (APT). Based on the EPMA results and a multilinear regression, a relation expressed as Cu = 0.98In + 1.81Sb + 0.03 can be calculated to describe the correlation between the elements. This indicates, that the incorporation mechanisms of In and Sb in the structure differ substantially. Indium is incorporated with the ratio Cu:In = 1:1 like in roquesite (CuInS2), supporting the coupled substitution mechanism 2Zn2+ → Cu+ + In3+. In contrast, Sb is incorporated with a ratio of Cu:Sb = 1.81:1. APT, which has a much higher spatial resolution indicates a ratio of Cu: Sb = 2.28: 1 in the entire captured volume, which is similar to the ratio calculated by EPMA, yet with inhomogeneities at the nanometer-scale. Analysis of the solute distribution shows two distinct sizes of clusters that are rich in Cu, Sb and Ag.

The Polythermal Section of Ti-22Al-xNb (30-78at.%Ti) in Ti–Al–Nb System

The polythermal section of Ti-22Al-xNb (30–78 at.% Ti) in the Ti-Al-Nb system was studied using X-ray diffraction analysis (XRD), differential thermal analysis (DSC), and electron probe micro-analysis (EPMA). No new ternary compounds were found in this work. The polythermal section has five three-phase regions, nine two-phase regions, and three single-phase regions. The O phase transition is confirmed to occur below 1000 °C. A four-phase invariant reaction β + σ → O + δ was found at 931 °C.

The new K, Pb-bearing uranyl-oxide mineral kroupaite: Crystal-chemical implications for the structures of uranyl-oxide hydroxy-hydrates

Kroupaite (IMA 2017-031), ideally KPb0.5[(UO2)8O4(OH)10]·10H2O, is a new uranyl-oxide hydroxylhydrate mineral found underground in the Svornost mine, Jáchymov, Czechia. Electron-probe micro-analysis (WDS) provided the empirical formula (K1.28Na0.07)Σ1.35(Pb0.23Cu0.14Ca0.05Bi0.03Co0.02Al0.01)Σ0.48 [(UO2)7.90(SO4)0.04O4.04(OH)10.00]·10H2O, on the basis of 40 O atoms apfu. Sheets in the crystal structure of kroupaite adopt the fourmarierite anion topology, and therefore kroupaite belongs to the schoepite-family of minerals with related structures differing in the interlayer composition and arrangement, and charge of the sheets. Uptake of dangerous radionuclides (90Sr or 135Cs) into the structure of kroupaite and other uranyl-oxide hydroxy-hydrate is evaluated based on crystal-chemical considerations and Voronoi-Dirichlet polyhedra measures. These calculations show the importance of these phases for the safe disposal of nuclear waste.