Epithermal Bicolor Black and White Calcite Spheres from Herja Ore Deposit, Baia Mare Neogene Ore District, Romania-Genetic Considerations
| Autor: | Réka Kovács, Ioan Denuț, Romulus Tetean, Alina Andreica, Călin Gabriel Tămaș, Ioan Mârza |
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| Rok vydání: | 2019 |
| Předmět: |
Baia Mare
lcsh:QE351-399.2 Geochemistry 02 engineering and technology 010502 geochemistry & geophysics Neogene 01 natural sciences Hydrothermal circulation chemistry.chemical_compound Vaterite Genetic model Herja calcite spheres 0105 earth and related environmental sciences Calcite Acicular gravitational concentration lcsh:Mineralogy Romania berthierite Geology 021001 nanoscience & nanotechnology Geotechnical Engineering and Engineering Geology Amorphous calcium carbonate chemistry jamesonite 0210 nano-technology Vein (geology) |
| Zdroj: | Minerals, Vol 9, Iss 6, p 352 (2019) |
| ISSN: | 2075-163X |
| DOI: | 10.3390/min9060352 |
| Popis: | White, black, or white and black calcite spheres were discovered during the 20th century within geodes from several Pb-Zn ± Au-Ag epithermal vein deposits from the Baia Mare ore district, Eastern Carpathians, Romania, with the Herja ore deposit being the maiden occurrence. The black or black and white calcite spheres are systematically accompanied by needle-like sulfosalts which are known by the local miners as “plumosite”. The genesis of epithermal spheres composed partly or entirely of black calcite is considered to be related to the deposition of calcite within voids filled by hydrothermal fluids that contain acicular crystals of sulfosalts, mostly jamesonite in suspension. The proposed genetic model involves gravitational concentration of sulfosalt acicular crystals towards the base of open spaces within paleochannels of epithermal fluid flow and the subsequent formation of calcite spheres by geochemical self organization of amorphous calcium carbonate that crystallized to calcite via vaterite. |
| Databáze: | OpenAIRE |
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