The Raman study of weathering minerals from the Coranda-Hondol open pit (Certej gold-silver deposit) and their photochemical degradation products under laser irradiation
Andrei Ionut APOPEI1,*, Nicolae BUZGAR1, Gheorghe DAMIAN1,2 & Andrei BUZATU1
1“Alexandru Ioan Cuza” University of Iaşi, Faculty of Geography and Geology, Department of Geology, 20A Carol I Blv., 700505 Iaşi, Romania, *e-mail: email@example.com
2Tech Univ Cluj Napoca, North University Center of Baia Mare, 62A Dr. Victor Babeş Street, 430083 Baia Mare, Romania.
The Canadian Mineralogist 12/2014; 52(6):1027-1038.
DOI:10.3749/canmin.1300054 · 1.13 Impact Factor
The Coranda-Hondol ore deposit (Certej, Romania) is a sulfide ore deposit that was mined primarily for gold, silver, lead, and zinc. Secondary minerals were formed through a precipitation process from sulfate solutions with a high concentration of dissolved metals (especially Fe). These sulfate solutions resulted from acid mine drainage. Fourteen waste samples were analyzed through Raman spectrometry, X-ray diffraction, and scanning electron microscopy. Fe3+-, Fe2+-, Cu-, Zn-, Ca-, Mg-, and MnAl-hydrated sulfates were identified. All are unstable when exposed to the laser beam of the Raman spectrometer. Coquimbite, copiapite, ferricopiapite, hydroniumjarosite, and gunningite turn into anhydrous forms or oxides, depending on the laser power. Gypsum turns into bassanite, while apjohnite loses all water molecules at 53.6 mW laser power on the surface of the sample. Rhomboclase, melanterite, rozenite, antlerite, and brochantite break down without forming new minerals. Fe2+-sulfates do not change into hematite under laser irradiation. Epsomite and hexahydrite are stable at 53.6 mW laser power.
Keywords: Raman spectrometry, weathering, sulfates, photochemical degradation, laser irradiation