title: Efflorescent sulfates from Baia Sprie mining area (Romania)--Acid mine drainage and climatological approach.
abstract: The Baia Sprie epithermal system, a well-known deposit for its impressive mineralogical associations, shows the proper conditions for acid mine drainage and can be considered a general example for affected mining areas around the globe. Efflorescent samples from the abandoned open pit Minei Hill have been analyzed by X-ray diffraction (XRD), scanning electron microscopy (SEM), Raman and near-infrared (NIR) spectrometry. The identified phases represent mostly iron sulfates with different hydration degrees (szomolnokite, rozenite, melanterite, coquimbite, ferricopiapite), Zn and Al sulfates (gunningite, alunogen, halotrichite). The samples were heated at different temperatures in order to establish the phase transformations among the studied sulfates. The dehydration temperatures and intermediate phases upon decomposition were successfully identified for each of mineral phases. Gunningite was the single sulfate that showed no transformations during the heating experiment. All the other sulfates started to dehydrate within the 30-90 °C temperature range. The acid mine drainage is the main cause for sulfates formation, triggered by pyrite oxidation as the major source for the abundant iron sulfates. Based on the dehydration temperatures, the climatological interpretation indicated that melanterite formation and long-term presence is related to continental and temperate climates. Coquimbite and rozenite are attributed also to the dry arid/semi-arid areas, in addition to the above mentioned ones. The more stable sulfates, alunogen, halotrichite, szomolnokite, ferricopiapite and gunningite, can form and persists in all climate regimes, from dry continental to even tropical humid.
authors.affiliation: "Alexandru Ioan Cuza" University of Iaşi, Department of Geology, 20A Carol I Blv., 700505 Iaşi, Romania. Electronic address: andrei.buzatu@uaic.ro.
authors.forename: Andrei
authors.initials: A
authors.lastname: Buzatu
authors.affiliation: Gottfried Wilhelm Leibniz University, Welfengarten 1 D-30167, Hannover, Germany.
authors.forename: Harald G
authors.initials: HG
authors.lastname: Dill
authors.affiliation: "Alexandru Ioan Cuza" University of Iaşi, Department of Geology, 20A Carol I Blv., 700505 Iaşi, Romania.
authors.forename: Nicolae
authors.initials: N
authors.lastname: Buzgar
authors.affiliation: Technical University Cluj Napoca, North University Center of Baia Mare, 62A Dr. Victor Babeş Street, 430083 Baia Mare, Romania.
authors.forename: Gheorghe
authors.initials: G
authors.lastname: Damian
authors.affiliation: "Alexandru Ioan Cuza" University of Iaşi, Department of Geology, 20A Carol I Blv., 700505 Iaşi, Romania.
authors.forename: Andreea Elena
authors.initials: AE
authors.lastname: Maftei
authors.affiliation: "Alexandru Ioan Cuza" University of Iaşi, Department of Geology, 20A Carol I Blv., 700505 Iaşi, Romania.
authors.forename: Andrei Ionuț
authors.initials: AI
authors.lastname: Apopei
keywords: Acid mine drainage; Baia Sprie; Climate; Ore deposit; Phase transformations; Secondary sulfates