hrvatski

Mineralni sastav ljuštura slatkovodnog puža Belgrandiella fontinalis i Belgrandiella kuesteri (Mollusca: gastropoda: Hydrobiidae)

X-ray powder diffraction (XRD) was used to study the mineral composition of shells of snails Belgrandiella fontinalis (F.Schmidt 1847) and Belgrandiella kuesteri (Boeters 1970) collected from three freshwater springs in northeastern Slovenia. It was found that the studied shells contained aragonite, calcite, dolomite and quartz. The fractions of minerals in particular shells were determined. XRD showed that the analysed gastropod shells consisted of two or more distinct inorganic layers. The outer shell layer for all species and all sampling localities contained aragonite. The outer layer of B. fontinalis collected at one locality, contained also a small fraction of calcite (~1 molar %) besides the dominant aragonite. Calcite was identified in the inner layer(s) of both studied species (2 to 3 molar %), while quartz was found only in B.kuesteri (5-7 molar %). However, both species sampled at one of the localities showed the presence of dolomite (about 20 molar %) in the inner layer(s). The presence of dolomite in the shells of adult gastropods and even molluscs is unusual. A possible formation mechanism and specific ecological factor which could influence the precipitation of dolomite in the shells of different Belgrandiella species is discussed.

Slatkovodni puž Belgrandiella fontinalis; Belgrandiella kuesteri. mineralni sastav

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