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1
Content available remote Luminescence characteristics of intraplate-derived olivines
EN
Olivine has so far attracted limited attention as a potential luminescence dosimeter. In particular, there is a dearth of information concerning the luminescence properties of geochemically characterised, pure olivine samples. Six well-characterised olivine samples from four intraplate settings are investigated in this study, including emission wavelengths and intensities, growth of signal with absorbed dose, signal stability and recovery of a given dose with a single aliquot regeneration (SAR) protocol. All tested olivines share a low-temperature (90–100°C) UV/blue thermoluminescence (TL) peak, and five of six samples also produce a low-temperature red/yellow emission. Higher temperature TL peaks, which would be thermally stable over geological timescales and could be used for dating, are rarely observed at low doses (c. 46 Gy), but detectable though dim at significantly higher doses (c. 460 Gy). Photostimulated luminescence (PSL) emissions are very dim, but reliably detected emissions are stimulated by blue, yellow and infrared (IR) light. PSL yielded generally successful dose recovery results; however, all tested signals are prone to significant anomalous fading and complex thermal transfer between unbleachable and bleachable traps. These characteristics must be addressed if olivine is to be used as a natural dosimeter for luminescence dating. Given the variety of luminescence responses, it appears that olivine samples in future dating work may need to be individually characterised prior to measurement.
PL
W artykule przedstawiono wyniki badań nowego materiału ceramicznego, w którym jako osnowę zastosowano piasek oliwinowy (olivine). Nowe tworzywo ceramiczne było badane pod kątem jego zastosowania w technologii wykonywania odlewów metodą wytapianych modeli. Materiał ten znajdzie głównie zastosowanie do wykonywania form samonośnych dla odlewów ze stopów aluminium oraz magnezu, zastępując stosowany dotychczas drogi materiał, jakim jest molochit (molochite). W artykule przedstawiono wyniki badań mineralogicznych piasku oliwinowego, a także badania termofizyczne nowego materiału ceramicznego sporządzonego na osnowie piasku oliwinowego. Wykonano badania porównawcze obu tworzyw, tj. na osnowie piasku oliwinowego i molochitu, a następnie dokonano oceny jakości nowego tworzywa ceramicznego. Przedstawiono również wyniki badań opracowanej ceramiki i jej przydatności do wykonywania odlewów.
EN
The article presents the research results of a new ceramic materiał, in which olivine sand was used as the matrix. This new ceramic materiał was studied at the angle of its application in the investment casting technology. This material will be mainly used for preparing self-supporting moulds for castings made of aluminium and magnesium alloys, replacing the expensive materiał - molochite which has been used so far. The article presents the results of mineralogical research of olivine sand, as well as thermophysical research of the new ceramic material made on the olivine sand matrix. Comparative research of both materials was conducted, i.e. with the olivine and molochite matrix, then the assessment of the quality of the new ceramic materiał was made. What is more, the research results of the developed ceramics and its usefulness for the production of castings are presented.
EN
The mining town of Røros located in central Norway was established in 1644 and it is known of historical mining industry related to copper. Røros was designated as an UNESCO World Heritage Site in 1980 on the base of mining culture represented by, e.g., unique wooden architecture. Slag pieces are composed of three parts differing in glass to crystallites ratio. Røros slags are composed of olivine- and pyroxene- group minerals accompanied by sulphides, with glass in the interstices. Temperature gradient and volatiles content were determined as the main factor influencing crystallization process in this material.
4
Content available remote Dry magnetic separation of olivine sand
EN
This paper investigates the potential for using dry magnetic separation to reduce the chromium content of a dried high quality olivine sand product in order to meet with anticipated future quality demands. The original feed contained 0.28-0.29% Cr2O3 of which approximately one third occurred as chromite and two thirds as chlorite. Two stage Permroll separation (at 0.50 T (max) and 0.92 T (max)) produced a concentrated product containing 0.13% Cr2O3 at a product recovery of 85.28%, thus reducing the chromium content by 55%. Some 80% of this reduction was achieved as a result of the first separation stage where chromite reported to the magnetic tailings at a recovery close to 100%. The chromium remaining in the concentrated product must be attributed to chlorite. Leachates obtained from leaching tests performed on the feed and the products were characterised by very low chromium concentrations, and the results suggest that chromium is more easily released from chlorite than chromite. This study shows that dry magnetic separation could be considered when a reduction of the chromium content of dried high quality olivine sand products is required.
5
Content available remote Obiekty przyrody nieożywionej wyspy Teneryfa
PL
W artykule zaprezentowano obiekty przyrody nieożywionej, typowe dla wyspy Teneryfa. Opisano skały występujące w obszarze Parku Narodowego Teide, w tym samego wulkanu Teide, a ponadto utwory odsłaniające się w obszarach Montana de Chinyero, Puerto de Santiago, Masca, Los Gigantes i Garachico. W obszarze Teneryfy dominują lawy, bazalty z widocznymi kryształami oliwinu, fonolity i skały maficzne. Można tu również spotkać trachity i andezyty, a na małych plażach czarny piasek wulkaniczny, zawierający pirokseny, oliwiny, skalenie oraz minerały żelaza (magnetyt).
EN
The objects of inanimate nature, typical for Tenerife Island were presented in this article. Rocks of the National Teide Park, including Teide Volcano, moreover rocks from outputs of Montana de Chinyero, Puerto de Santiago, Masca, Los Gigantes and Garachico were described there. Lavas, basalts with visible olivine Crystals, phonolites, and maphic rocks dominate in the area of Tenerife Island. Moreover it is possible to find there trachytes and andesites and on the beaches, black, volcanic sand with pyroxenes, olivines, feldspars and iron minerals (magnetite).
EN
Application of the „Chvorinov’s rule“ for calculation of the total time of casting solidification made also possible to determine chilling effect of foundry moulds (coefficient of heat accumulation of the mould, bf) with use of mixtures with new kinds of non-quartz base sands (Magnesite, Chromite, Olivine, Dunite, Kerphalit). Processes by several authors (G. Halbart, A. I. Vejnik, G. A. Anisovich) were used for mathematical treatment of measurement results and determination of bf. The highest values were achieved for magnesite moulds followed by chromite ones; the lowest values, approximately half-ones, represented the Dunite moulds. At the same time the results made possible to determine „the Chvorinov’s mean solidification constants“ (k) that are in direct proportional dependence on bf and indirect proportional to solidification time (τ1).
EN
It was suggested that perhaps Mössbauer parameters of troilite could serve as a criterion for an interpretation of the origin of various meteorites. It was found that in three meteorites coming from the same parent body (Baszkówka, Mt. Tazerzait and Songyuan) the angle between the principal axis of the electric field gradient (EFG) and the direction of the magnetic field in troilite is around 60o. Further investigations showed that in some other meteorites, not belonging to this group, this angle is close to 90o.
PL
Uzyskano bardzo wysoką zgodność obliczonych równowagowych stałych sieci forsterytu z wartościami znanymi z pomiarów laboratoryjnych. Obliczenia zostały przeprowadzone przy zastosowaniu teorii funkcjonału gęstości (DFT) w ramach uogólnionego przybliżenia gradientowego (GGA). Uzyskano również generalnie dobrą zgodność zmian gęstości forsterytu wraz ze wzrostem ciśnienia z modelami globu.
EN
Preliminary results of calculation of selected elastic constants of olivine (forsterine - Mg_2SiO_4) under high pressure are presented. Pressures in the 0-80 GpA have been used. Density and bulk modulus as a function of pressure have been calculated as well. All calculations have been performed using Density Functional Theory (DFT) within Generalized Gradient Approximation Framework (GGA). Application of obtained results for interpretation of deep geophysical studies was disscussed.
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