Naslov
Authigenic mica in Early Miocene volcaniclastic rocks of the Macelj area, Hrvatsko zagorje, Croatia

Autori
Tibljaš, Darko ; Šćavničar, Stjepan ; Molin, Gianmario ; Slavković, Renata

Izvornik
Neujes Jahrbuch für Mineralogie-Monatshefte (0028-3649) (2004), 2; 69-82

Vrsta, podvrsta i kategorija rada
Radovi u časopisima, članak, znanstveni

Ključne riječi
altered volcaniclastics; authigenic mica; celadonite; Croatia; glauconite; Miocene

Sažetak
In the Early Miocene zeolitized volcanicalstic rocks from NW part of Hrvatsko zagorje green authigenic mica occurs in thin veins and coatings of glass shard vesicles. X-ray powder pattern with widened but still relatively sharp reflections is characteristic for 1M micas, with Fe-rich octahedral sheet. The observed value d(060) is 1.508 &Aring ; . IR spectrum is characterized by sharp absorption bands in the OH stretching region, with two strongest bands at 3580 cm-1 and 3600 cm-1 ascribed to Al-Fe3+ and Al-Mg cationic environment of the OH groups. Microprobe analyses revealed that this is an interlayer-deficient dioctahedral mica, with Al as dominant cation in octahedral sheet, viM3+>1.2, and low tetrahedral substitution, with quite peculiar chemical composition that does not correspond ideally to any member of the mica group.

Izvorni jezik
Engleski

Znanstvena područja
Geologija

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