Geologia Croatica, Vol. 65 No. 1, 2012.
Original scientific paper
https://doi.org/10.4154/GC.2012.05
Mineralogical and geomicrobiological investigation of phosphorite from Ervenik, Croatia
Vladimir Bermanec
; Faculty of Science, University of Zagreb, Horvatovac 95, 10000 Zagreb, Croatia
Hrvoje Posilović
; Faculty of Science, University of Zagreb, Horvatovac 102a, 10000 Zagreb, Croatia
Željka Žigovečki Gobac
; Faculty of Science, University of Zagreb, Horvatovac 95, 10000 Zagreb, Croatia
Jasna Hrenović
; Faculty of Science, University of Zagreb, Rooseveltov trg 6, 10000 Zagreb, Croatia
Nevenka Mikac
; Rudjer Bosković Institute, Bijenička 54, 10000 Zagreb, Croatia
Goran Kniewald
; Rudjer Bosković Institute, Bijenička 54, 10000 Zagreb, Croatia
Abstract
Phosphate minerals hydroxylapatite, fluorapatite and crandallite were identified in nodules within phosphorites from Ervenik, Croatia. The minerals were identified using optical microscopy, XRD, SEM and EDX analyses. The presence of fungi was recognized only in association with phosphate-rich phases. Fungal activity resulted in the dissolution of apatite, producing hollow crystals, particularly in hydroxylapatite – enriched zones. A substantial number of hyphae were observed on the surface of phosphate minerals, in addition to saprophytic bacteria and bacterial spores. Induced activity of phosphate-accumulating bacteria in an aquatic environment caused dissolution of the phosphate minerals. The aqueous phase contained increased concentrations of several elements, including Ca, Sb, U, V and As. These elements are important constituents of minerals of the apatite group. As a consequence of the crystallization of apatite, the concentration of phosphate decreases with a corresponding increase in aluminium concentration, resulting in the prevalence of crandallite as the stable phase, forming the outer sector of the spherulites.
Keywords
phosphorite; hydroxylapatite; fluorapatite; crandallite; fungi; bacteria
Hrčak ID:
78324
URI
Publication date:
24.2.2012.
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