886 KB32 KB200320222003Dolenec, Tadejštevilka:2letnik:50str. 453-466ISSN:1408-7073COBISSID_HOST:438622URN:URN:NBN:SI:doc-8ACPTWCHenInštitut za rudarstvo, geotehnologijo in okoljeNaravoslovnotehniška fakultetaRMZ-materials and geoenvironmentCentral AdriaticJabučka kotlinaJabuka PitSEM and EDS studySEM in EDS študijsrednji JadrantodorokittodorokiteXRDTodorokite - a 10 A manganate from the Jabuka Pit (Central Adriatic)| todorokit - 10 A manganat z Jabuške kotline (srednji Jadran)|Additional studies of ferromanganese crusts and coatings from the Jabuka Pit, a depression up to 275 m deep in the Central Adriatic, revealed the presence of todorokite. This mineral was recognized as the major constituent of an Fe-poor and Mg-rich 10 A manganate phase, forming an up to 1 mm high stalactitic structures composed of about 4 micrometers long plate-like crystals, as well as of collomorph-banded and botryoidal aggregates, found on shells and shell fragments of Ostrea cochlear Poli exposed to seawater. The exact mechanism of todorokite precipitation in the Jabuka Pit is still unknown. However, we hypothesized its hydrogenous precipitation at the sediment-water interface in oxygenated conditions at Eh around 0.5 V and pH around 8.18V okviru nadaljnih raziskav feromanganovih prevlek in skorij, iz do 275 m globoke Jabučke kotline v srednjem Jadranu, smo ugotovili prisotnost todorokita. Gre za 10 A manganat reven z Fe in obogaten z Mg, ki smo ga našli na lupinicah in odlomkih školjke Ostrea cochlear Poli, kjer v glavnem tvori do 1 mm velike stalaktitom podobne tvorbe sestavljene iz okrog 4 mikrometrov velikih ploščic in kolomorfne oblike ter sferične agregate. Njegov nastanek na območju Jabučke kotline še ni povsem jasen. Zaenkrat predpostavljamo, da se izloča pri oksidacijskih pogojih in sicer pri Eh okrog 0.5 V ter pH okrog 8.18 na meji sediment - morska vodaTEXTznanstveno časopisjejournalsSlovenian National E-content AggregatorNational and University Library of SloveniaUniverza v Ljubljani, Naravoslovnotehniška fakulteta