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Wyświetlanie 1-3 z 3
Tytuł:
Gemstones of eastern Kazakhstan
Autorzy:
Chlachula, Jiri
Powiązania:
https://bibliotekanauki.pl/articles/94440.pdf
Data publikacji:
2020
Wydawca:
Uniwersytet im. Adama Mickiewicza w Poznaniu
Tematy:
Altai
non-metallic mineral deposits
gemstone
decorative stones
prehistory
field exploration
jewellery
Ałtaj
kamienie szlachetne
kamienie ozdobne
prehistoria
badania terenowe
biżuteria
Opis:
An overview is presented of gemstones from eastern Kazakhstan in terms of their geographical distribution, geological provenance and genesis, gemmological characteristics, historical use and current applications. Locally occurring precious, semi-precious and decorative stones were extracted and traded along the northern part of the Silk Road that traversed the area in earlier historical times. Currently, non-metallic minerals, which largely originate from mafic igneous and metamorphic bodies of the Altay and Kalba Mountains of Kazakhstan, still are insufficiently known and exploited industrially only marginally. For the present study, selected depositories of coloured stones at the Mineralogy Museum of the East Kazakhstan State Technical University were used, supplemented by the newly collected material during personal fieldwork in the southern Altay between 2005 and 2015. Standard documentation of the gemstones selected is provided, alongside with their known occurrence sites and an evaluation of the perspective gemstone-bearing deposits with respect to regional morphostructural bedrock characteristics. The most precious gemstones include topaz, corundum (sapphire and ruby), beryl (emerald and aquamarine), coloured tourmalines, agates as well as diamonds. Despite the great variety, the majority of these traditionally most valued stones are currently commercially not viable, unlike high-quality decorative stones.
Źródło:
Geologos; 2020, 26, 2; 139-162
1426-8981
2080-6574
Pojawia się w:
Geologos
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
The assemblages of transparent heavy minerals in Quaternary sediments of the Kielce-Łagów Valley (Holy Cross Mountains, Poland)
Autorzy:
Ludwikowska-Kędzia, Małgorzata
Powiązania:
https://bibliotekanauki.pl/articles/94365.pdf
Data publikacji:
2013
Wydawca:
Uniwersytet im. Adama Mickiewicza w Poznaniu
Tematy:
heavy mineral analysis
Quaternary deposits
Holy Cross Mountains
analiza ciężkich minerałów
złoża czwartorzędowe
Góry Świętokrzyskie
Opis:
The composition of the transparent heavy-mineral assemblages (0.25-0.1 mm) in Quaternary slope, karst, glacial, fluvioglacial and fluvial deposits with different parent material was investigated in the Kielce-Łagów Valley (the central part of the Palaeozoic core of the Holy Cross Mountains). For the purpose, 93 samples of mostly sandy sediments were examined. Some marker and some supporting minerals can be distinguished. Slope and karst deposits are dominated by the abrasion-resistant minerals zircon, tourmaline, staurolite and rutile. This assemblage points at a source consisting of strongly weathered pre-Quaternary bedrock. Glacial and fluvioglacial deposits are dominated by medium-resistant and non-resistant minerals (garnet, amphibole, pyroxene and biotite). The two types of parent material of the heavy minerals are typical of the Quaternary deposits in the Polish uplands. The two sources are most clear in the younger (Vistulian and Holocene), mostly fluvial sediments. The results of the analysis imply that the impact of Pleistocene glaciers on the central part of the Holy Cross Mountains was neither large enough to hide the local mineralogical background, nor sufficient to dominate over the main processes transforming the mineral composition under the variable climatic conditions of the Quaternary, including aeolian processes and chemical weathering.
Źródło:
Geologos; 2013, 19, No. 1-2; 95-129
1426-8981
2080-6574
Pojawia się w:
Geologos
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Heavy-mineral assemblages from fluvial Pleniglacial deposits of the Piotrków Plateau and the Holy Cross Mountains - a comparative study
Autorzy:
Wachecka-Kotkowska, Lucyna
Ludwikowska-Kędzia, Małgorzata
Powiązania:
https://bibliotekanauki.pl/articles/94384.pdf
Data publikacji:
2013
Wydawca:
Uniwersytet im. Adama Mickiewicza w Poznaniu
Tematy:
heavy mineral analysis
fluvial deposits
Vistulian
Pleniglacial
central Poland
Holy Cross Mountains
Piotrków Plateau
analiza ciężkich minerałów
osady rzeczne
Wisła
środkowa Polska
Góry Świętokrzyskie
Opis:
The heavy-mineral assemblages of Pleniglacial fluvial sediments were analysed for two river valleys, viz. the Luciąża River (at Kłudzice Nowe) and the Belnianka River (at Słopiec). These sites, on the Piotrków Plateau and in the Holy Cross Mountains respectively, are located in different morphogenetic zones of Poland that were affected to different degrees by the Middle Polish ice sheets. The study was aimed at determining the kind of processes that modified the heavy-mineral assemblages in the two fluvial sediments, at reconstructing the conditions under which these processes took place, and in how far these processes caused changes in the assemblages. The heavy-mineral associations of the parent material was taken as a starting point; this parent material were the sediments left by the Odranian glaciation (Warta stadial = Late Saalian). It was found that heavy-mineral assemblages in the Luciąża valley deposits are varied, particularly if compared with other fluvioglacial Quaternary deposits from the Polish lowlands, with a dominance of garnet. In the fluvial deposits of the Belnianka valley, zircon, staurolite and tourmaline dominate, with minor amounts of amphibole, pyroxene, biotite and garnet. This suggests that the deposits were subject to intensive and/or persistent chemical weathering and underwent several sedimentation/erosion cycles under periglacial conditions. In both valleys chemical weathering and aeolian processes were the main factors that modified the assemblages of the transparent heavy minerals; these processes were largely controlled by the climatic changes during the Pleistocene.
Źródło:
Geologos; 2013, 19, No. 1-2; 131-146
1426-8981
2080-6574
Pojawia się w:
Geologos
Dostawca treści:
Biblioteka Nauki
Artykuł
    Wyświetlanie 1-3 z 3

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