Year: 1996
Type: article
Abstract: Serpentine mineral samples come from some metaultramafic bodies included in the geological fom1ations of the Romanian Carpathians.For tl1e most pmt of the sm11ples mesh-textme m-e chm•acteristic.Its one is detemilned due to tl1e substituted processes of tl1c olivcne or/m1d pyroxene by chrysolile ancl/or lizm-clite in the mm-ginalzones, m1d m1tigorite in the central ones.Sometimes, some small m1tigorite ±1asks me spread in the serpentine mass.Crystallochemical data have been calculated according to M6N40JO(OH)s.general formula, whereM=Mg, Fe2+, Ni, Fe3+, sometimes Cr m1d N=Si, AI.However, Si m1d AI contents show some evident substituted processes in tl1e tetrahedral levels, between Si m1d Al.Alack of silica in these levels, in the calculated formula suggests a completion of tl1ese ones by Fe3+ cations.Mg, Ni, Fe2+, Fe3+ cations were identified as filling of tl1e octahedral chains.The exchanges between Mg m1d other above mentioned cations m-e insignificantly, so iliat tl1eir sum vmies an10ng 0.267-0.617.Sometimes AI cations m-e presented in tl1ese structmallevels.IR absorption spectra confim1 tl1ese substitutions processes, registering absorption bands at ilie chm•acteristic fi•equencies (em-I).However tl1e registered bands about 610 em-! vmies clirectly proportional to tl1e Mg substitution by Fe,Ni.Cr. at tl1e octahedral levels.Its intensity increases when Mg content is increasing.There is no possibility to evidence tl1e proportion in which took place iliis substitution, but some possible combination would be suppose, MgMgMg, NiMgMg, NiFeMg, FeFeMg, FeMgMg, sometimes CrNilV!g or CrFeMg.Some of IR spectra present at ilie 663cm-I fi•equency a very low intensity peal.;, which could be assigned to NiNil\li combination.These high inhomogeneous and discontinuous substitutional ex-chm1ges in the octahedral level have detemuned iliese vmiations of tl1e IR absorption data At OH-stretcl1ing region, about tl1e 3700 em-! domain the allures of the curves m•e sin1ilm• to these ones chmacteristics for low Ni content.
Authors: J. Schneider, H. L. Meyerheim
Language: English
Subfield: Geochemistry and Petrology
Field: Earth and Planetary Sciences
Domain: Physical Sciences
Open Access status: bronze
OpenAlex ID: W2329584161