Epithermal bicolor black and white calcite spheres from Herja ore deposit, Baia Mare neogene ore district, Romania

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Marco E. Ciriotti
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Iscritto il: ven 25 giu, 2004 11:31
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Epithermal bicolor black and white calcite spheres from Herja ore deposit, Baia Mare neogene ore district, Romania

Messaggio da Marco E. Ciriotti » dom 09 giu, 2019 12:23

Dall'unica rivista ISI internazionale sempre attiva, che non si ferma mai e cioè lavora anche nei week-end e non fa vacanze… e quindi, come dice Federica Zaccarini, segue il ciclo della scienza che non si ferma mai...

Referenza:
▪ Mârza, I., Tămaș, C.G., Tetean, R., Andreica, A., Denuț, I., Kovacs, R. (2019): Epithermal Bicolor Black and White Calcite Spheres from Herja Ore Deposit, Baia Mare Neogene Ore District, Romania - Genetic Considerations. Minerals, 9, 352; https://doi.org/10.3390/min9060352

Abstract:
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.
Marco E. Ciriotti

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