Boros István (szerk.): A Magyar Természettudományi Múzeum évkönyve 50. (Budapest 1958)

Kaszanitzky, F.: Genetic relations of the Pátka-Kőrakáshegy ore occurrence, Velence area, North Central Hungary

There was only one single phase of ore mineralization out of ascendent solutions. With the decrease of temperature the chalcopyrite and tetrahedrite occurring in sphalerite in the form of isomorphous admixtures have been unmixed and this process gave rise, because of the similarity of structures, to the formation of oriented intergrowths. The ore mineralization has in its bulk proceeded at a low temperature (mostly epithermal in its bulk) as corroborated by the following observations : 1. The presence of colloidal sphalerite in the material of the fissure filling. 2. The development of the sphalerite crystals in dodecahedral form, as proven by structural etching. 3. The occurrence of rhombic chalcocite as a primary mineral. 4. Unmixing products indicative of higher temperature (cubanite, sphalerite asterisks) are lacking in chalcopyrite. The sequence of formation of the minerals partaking in the paragenesis has been established in the following : pyrite I, chalcopyrite I, sphalerite, galena, chalcopyrite II, tennantite, tetrahedrite, chalcocite I, pyrite II, antimonite, fluorite ; secondary minerals : chlacocite II, covellite, azurite, malachite, cinnabar, cerussite, ochre of antimony. Of the non-metallic secondary minerals gypsum was found. The following elements take part in constituting the ore material : 0, Si, Zn, Pb, S, Ca, F; Fe, Cu, Ag; Cd, Sn, As, Sb, Bi, Mo, Mii, Ni, Co, Ge, Hg. The predominant elements of the occurrence have been emphasized by italics. The elements printed in heavy type are those which could be demonstrated by the methods of chemical analysis. The rest has been demonstrated by spectrography. There are some interesting conclusions to be drawn from the paragenesis of ore mineralization, the surface-near location of the deposit and the lack of an oxidation-cementation zone. The mineralization of the Kőrakáshegy is considered by the former investigators of the area (B. J a n t s k y, J. K i s s) to have been connected with the hydrothermal phase of the post-magmatic activity of granite and to be in consequence Palaeozoic of age. Our research has given different results. If the mineralization should have been connected with the hydrothermal phase above named, i. e. Carboniferous-Permian in age, the lack of the oxidation zone would be difficult to interpret. This lack could only be explained by assuming an erosion of such a degree that it kept pace with the downward progress of the oxidation zone. In this case the ore mineralization should have originated in so great a depth below the ancient surface as to make the formation of epithermal ores altogether impossible. Ore minerals, cementing the silicatic material filling the fissures, are younger than was supposed by the investigators of the area. We consider this opinion of ours to be entirely corroborated by the above stated facts. However, it is not possible to determine the age of ore mineralization any closer, although a connection between the adjacent andésites of Eocene age and the Pátka mineralization seems to us not altogether impossible. Bibliography : 1. Föl d v á r i. A.: Jelentés a pátkai fluorit kutatás 1949 T. 31-i állapotáról (1940, manuscr.: Magyar Állami Földtani Intézet Irattára, Budapest, 1940). — 2. Földvári, A.: A szabadbattyáni ólomérc és kövületes karbonelőfordulás (MTA Mfísz. Tud. Oszt. Közi., 5, 1952). — 3. J a n t s k y, B.: A Velencei hegység földtani és kőzettani viszonyai (MÁFI Évi Jelentés, 1950). — 4. J a n t s k y, B.: A Velencei hegység hidrotermális ércesedése (MTA Mfísz. Tud. Oszt. Közi. 1952). — 5. J a n t s k y, B.: A Velencei hegység földtana (manuscr. 1956). —-6. Kiss, J : A Velencei hegység északi peremének hidrotermális ércesedése (MÁFI