Stjepan Šćavničar

Childrenite and crandallite from the Stari Trg mine (Trepča), Kosovo: new data

SummaryChildrenite and crandallite are described as two new phosphate members in the paragenesis of the Stari Trg mine which comprises vivianite, ludlamite and struvite. Crandallite crystals with very simple rhombohedral habit grow on rhombohedral carbonate and childrenite crystals. The crystal morphology of childrenite is very similar to that at described from other localities. Following forms were measured: {100}, {100}, {110}, {120}, {121}, {221} and {342}. The average chemical composition is Ch91 Eo9 (Ch-childrenite, Eo-eosphorite). Pseudo-orthorhombic unit cell dimensions were calculated: a = 10.390(4) A, b = 13.390(4) A and c = 6.920(2) A. Growth sectors and sector twins of childrenite are described.ZusammenfassungChildrenit und Crandallit werden als zwei neue Minerale der Phosphatgruppe beschrieben. Sie stammen aus der Stari Trg Grube in Paragenese mit Vivianit, Ludlamit und Struvit. Die Crandallit-Kristalle mit einfachem rhomboedrischen Habitus, wachsen rhomboedrischen Karbonat- und Childrenit-Kristallen auf. Die Kristallmorphologie von Childrenit ist, verglichen mit der aus anderen Lokalitäten, sehr einfach. Folgende Formen wurden gemessen: {100}, {010}, {110}, {120}, {121}, {221} und {342}. Die durchschnittliche chemische Zusammensetzung ist Ch(91Eo9(Ch-Childrenit, Eo Eosphorit). Eine Kalkulation der pseudo-orthorhombischen Elementarzelle ergab folgende Abmessungen: a = 10.390(4) A, b = 13.390(4) A and c = 6.920(2) A. Schließlich wird das Wachstum and die Zwillingsbildung von Childrenit beschrieben.

Hedyphane from Nezilovo, Macedonia

Two different members of lead calcium arsenate series of apatite group from Nezilovo are found. According to the chemical formula (calculated on the basis of 10 cations), infra red absorption powder spectra, X-ray powder patterns and unit cell dimensions these are two distinct members of one mineral species. Unit cell dimensions are a=10.157(3), c=7.256(6) and a=10.154(2), c=7.191(3) A. The first sample has Pb:Ca ratio 7.35:2.59 and the second one 6.54:3.45, what is closer to ideal hedyphane formula (6:4).

Uranium Minerals in the Radlovac Series Metasediments at Mt. Papuk, Croatia

Applying a combination of different methods – X-ray diffraction, scanning electron microscopy, gamma-spectroscopy and X-ray spectroscopy, a suite of uranium minerals, meta-torbernite, meta-uranospinite and meta-zeunerite was identified in metasediments of the Radlovac series at the Mt. Papuk area, Croatia. The accessory minerals galenaa, zircon, rutile, chalcopyrite and cuprite, as well as an unidentified Ni-bearing phase are also present. The mineral assemblage indicates a sequence of epigenetic and supergene processes affecting the Radlovac series.

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

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 A . 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.