[en] The anomalous reductions in the energy band gap of the chalcopyrite semiconductors as compared to their relative binary analogs are estimated quantitatively by using a simple relation that involves quantum defect electronegativity scale and the average principal quantum number. The chemical and the structural contribution to this anomaly is discussed in details and it is shown that the relation can be easily extended to explain the variation in the band gap of some cross-substitutional alloys

No abstract available

[en] A new method for in situ S isotopic analysis was tested using a laser ablation system together with a multi-collector (MC)-ICPMS. The method was tested for the analysis of pyrite, pyrrhotite, chalcopyrite and pentlandite using a large pyrite crystal as an in-house standard. Repeated measurements of Py, Pn, Po and Cpy provide an average internal precision of less than 0.1 per mille (2σ). The method was also applied to a pyrite-bearing orogenic Au deposit to display the ability of the method to resolve minor variations in δ ³⁴S across growth zoning in pyrite

[en] For Moessbauer studies of the Morasko meteorite three different samples were isolated: troilite, kamacite and taenite. Investigated spectra revealed new mineralogical phases: taenite, tetrataenite and antitaenite. That is first such identification in meteorite found in Poland.

[en] CuInsub(1-x)Fesub(x)Te₂ crystal samples with x varying from 0 to 1 have been grown by a programmed-directional-freezing technique. All compounds with x<=0.3 had a single-phase chalcopyrite structure, whereas secondary-phase formation has been observed for x>0.3. Indications of anomalous behaviour in the electrical and magnetic properties at x approx.= 0.1 could be explained due to the delocalization of d electrons originating from the p/d mixing and due to the strong covalence of the chalcopyrite compounds

[en] Different degrees of similarity between inorganic crystal structures are defined concisely and examples are presented that illustrate their practical application. A notation giving the coordination of atoms is presented together with some basic rules for developing crystal-chemical formulae and the Bauverband description of inorganic structure types. Typical examples of the nomenclature are: pyrite Fe^[6o]{g}[S₂^[3;1)t]], F(□2l)+F'FeS₂ Paanti 3; spinel Mg^[4]Al₂^[6]O₄, _∞³[Mg^[4t]Al₂^[6o]O₄^[1,3;12co], F'''₂₂₂+C, T'MgAl₂O₄ Fdanti 3m. (orig.)

[en] Thirty eight lead isotope analyses made on the Devonian sulphide mineralization of Chessy (Rhone) provide new data on the composition and sources of the hydrothermal fluids that gave rise to the massive sulphide ores of the Brevenne volcanosedimentary district. A partial mantle origin is indicated for the main episode of mineralization, with a remarkable homogeneity in the isotopic signatures of the different ores of the Chessy massive sulphide deposit (galenas with ²⁰⁶Pb/²⁰⁴Pb = 18.163 and ²⁰⁷Pb/²⁰⁴Pb = 15.558). This mantle contribution resulted from leaching, by the mineralizing fluids, of the tholeiitic facies of the underlying volcanic pile. A second episode of mineralization, also associated with submarine silicic volcanic activity, did not give rise to economic concentrations. It is characterised by lead isotope signatures that are more radiogenic (²⁰⁶Pb/²⁰⁴Pb > 18.34 and ²⁰⁷Pb/²⁰⁴Pb > 15.63) without mantle participation

[en] The determination of Moessbauer spectra for two groups of samples are introduced. One group is gold bearing fractural quartzvein type and altered type with different phases of mineralization. In that group, 11 samples are collected in defferent positions in the midpart of No.1 body of Xincheng goldmine and 8 samples are collected in Shangdong Linglong mine and Xincheng mine. The other group consists of 5 samples of intact rocks in the drill holes of ZK 103 and ZK 92 in profile 183. The corresponding variation can be observed in spectral width and the probability of recoilless for pyrite samples with different phases of mineralization. The data are useful for studing mechanism of mineralization of goldmine. This is a priliminary exploration for giving a quantitative indication of mineralization and alteration

[en] By employing the first-principles method of the full potential linear augmented plane waves plus the local orbitals (FP−L/APW+lo) within the generalized gradient approximation for the exchange and correlation potential, the structural, electronic, and magnetic properties of chalcopyrite compound CdCrO₂ are investigated. In order to take into account the strong on-site Coulomb interaction, we also performed the generalized gradient approximation plus the Hubbard correlation terms. We systematically study how the exchange interactions and magnetic moments of CdCrO₂ are affected by the different choice of U as well as the exchange correlation potential. We have also carried out the pressure effect on the magnetic properties. - Highlights: ► The calculation of the exchange constants. ► The pressure dependence of the magnetic properties. ► The exchange correlation potential effect on the magnetic properties.

[en] It is often necessary during processing of uranium ore to flotate pyrite at sodium carbonate alkaline pH value caused by the subsequent hydrometallurgical process stages. It was found out by ESCA analyses that the pyrite surface changes chemically prior to the addition of flotation agents. FeS₂ becomes FeO within a few hours in the case of storage in process water; limonite and/or geothite result from pyrite. The copper ions of the activator CuSO₄ are exclusively monovalent on the pyrite surface. The resulting heavy metal xanthogenate is Cu(I) xanthogenate. Conclusions are derived for the flotation practice for the intensification of the reagent regime. (orig./HP)