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- Title
The first cave occurrence of orpiment (As<sub>2</sub>S<sub>3</sub>) from the sulfuric acid caves of Aghia Paraskevi (Kassandra Peninsula, N. Greece).
- Authors
Lazaridis, Georgios; Melfos, Vasilios; Papadopoulou, Lambrini
- Abstract
Orpiment, tamarugite and pickeringite occur in close association above the surface of thermal water cave pools in the active sulfuric acid caves of Aghia Paraskevi on the Kassandra peninsula, northern Greece. Gypsum also occurs as small interstitial crystals or encrustations. Orpiment is of high significance since it has not previously been reported as a cave mineral. In addition, tamarugite and pickeringite rarely occur in karst caves. Water from a borehole and a spring is of Na-Cl type and contains traces of CO2 and H2S. The B/Cl ratios indicate seawater participation with a possible mixing with geothermal water of meteoric origin. Oxidation of fumarolic H2S and incorporation of seawater is a possible cause for the deposition of tamarugite. Orpiment accumulated from vapors under sub-aerial conditions at low temperatures in acidic conditions through an evaporation-condensation process. Fluid cooling and/or acidification of the solution resulting from H2S oxidation were responsible for orpiment precipitation. Oxidation of H2S to sulfuric acid dissolved the limestone bedrock and deposited gypsum.
- Subjects
KASSANDRA Peninsula (Greece); GREECE; CAVES; ARSENIC sulfide; SULFURIC acid; GYPSUM; INCRUSTATIONS; OXIDATION
- Publication
International Journal of Speleology, 2011, Vol 40, Issue 2, p133
- ISSN
0392-6672
- Publication type
Article
- DOI
10.5038/1827-806X.40.2.6