Papp Gábor - Szakáll Sándor - Weiszburg Tamás szerk.: Az erdőbényei Mulató-hegy ásványai (Topographia Mineralogica Hungariae 1. Miskolc, 1993)

Az erdőbényei Mulató-hegy Si02-ásványai (Molnár Ferenc - Takács József)

Tokody, L. (1962): Mineralien von Erdőbénye. Acta Geol. Hung., 7, pp. 315-349. Wollaert, E., Landuyt, V. & Landuyt, J. (1990): Characterization of gem opal and inferior opal qualities by means of electronmicroscopy. Zeitschr. Deutsch. Gemmol. Ges., 37 (4), pp. 211-223. Zimányi K. (1894): Quarc Tolcsváról, Zemplén megyében. Földtani Közlöny, 24, pp. 360-364. Silica minerals of Mulató Hill, Erdőbénye (NE Hungary) by Molnár, F. & Takács, J. Various Si02-modifications found at Mulató Hill, Erdőbénye were studied. (Specimens were supplied from the collections of the Herman Ottó Museum, Miskolc, and from the Hungarian Natural History Museum, Budapest.) On the basis of micromorphological, optical, X-ray diffraction and transmission electron microscope studies the main conclusions are as follows: I. Quartz (Figs. 1-4) and opal (Figs. 5-13). Earlier studies (Tokody, 1962; Kulcsár & Barta, 1971) revealed the presence of two (an older, "pneumatolytic", and a younger, hydrothermal) quartz generation. Present study focussed on the hydrothermal quartz and opal varieties. 1. The hydrothermal crystallization of quartz and opal varieties followed the carbonate paragenesis. 2. The cavities contain either predominantly quartz or exclusively opal varieties. 3. The succession of opal encrustations and quartz varieties was driven by the saturation-supersaturation properties of the Si02-water system (Fig. 20). The micromorphology of the opal surface and the observations in thin sections suggest that the normal succession (opal, chalcedony-quartzin, quartz) was disturbed by local saturation, dissolution and evaporation phenomena. 4. The opal varieties belong to the "opal-C" and "opal-CT" groups according to the X-ray diffraction data. These varieties (previously called as "lussatite") show anomalous anisotropism and fibrous structures in thin sections.