Boros István (szerk.): A Magyar Természettudományi Múzeum évkönyve 51. (Budapest 1959)

Kaszanitzky, F.: Genetic relation of ore occurrence in the Western Mátra Mountains, North Eastern Hungary

small grains shows them to be semseyite. — Boulangerite is mentioned by Sztrókay. The present author failed to encounter it in his samples. Neither has he found miargyrite, also mentioned by Sztrókay. However, some very small grains, turning rapidly black upon intense lighting, can possibly consist of miargyrite. The complex sulphides are lacking from the sections of the veins below the level of the main gallery. Only the —50 metre level of the Károly vein has yielded some bournonite grains. The formation of the complex sulphides has apparently taken place at a low temperature. Antimonite is one of the youngest minerals of the association. It occurs on the upper levels of the Károly, Arany Péter and Aranybányabérc veins only. It is a rather scarce mineral. It forms infrequent radial concentric aggregates in the kaolinitized gangue of the veins. Its need-like automorphous grains are of 2—3 centimetres length. The microscope has revealed pressure twinning. Sztrókay has called attention to the resemblance to Kisbánya and Borpatak antimonites, regarding the multitude of forms of the prism zone. Marcasite occurs throughout together with the young pryrite generation, excepting the "2150" vein. It was not encountered on the deeper levels of the Károly vein. An abundance of any importance was found, however, in the Szákacsurgó vein only. Automorphic crystals of marcasite occur along the borders of pyrite aggregates or in the interior of young pyrite of gel structure. In the first case, the pyramid faces are developed best, while the second type is characterized by the prism. Twinning is very common. The marked anisotropy of marcasite serves to distinguish it from pyrite. Of the gangue minerals there occur, beside the ones already treated, f luorite, baryte, coelestine and gypsum in small amounts. Koch has also discovered laumontite in the main gallery. The small turquoise or light violet phenocrysts of fluorite occur in the host rock as well as in the gangue. The crystals are of hexahedral or octahedral shape. Crystals of microscopic size occuring in the veins are generally connected with wurtzite. The aggregates of small tabular crystals of baryte sometimes grow through quartzite in a fanlike arrangement. Greater amounts of baryte were found in surface outcrops of the Keresztes vein. The automorphous crystals of some millimetres size of coelestine are quite rare. They are invariably covered by gypsum crystals. Gypsum sometimes occurs in water-clear lumps of fist size. No crystal form can be determined. Of secondary ore minerals, the presence of chalcocite, covelline and cerussite in minute amounts has been established in the surface-near parts of the veins. No oxidation zone carrying abundant ore was developed in the veins of the occurrence. The ore minerals of the surface-near parts of the veins were leached by descendent solutions. Weathering has especially affected gelena. However, the investigation of the surface-near vein sections and of the structure of the vein outcrops has led us to believe that the upper parts of the veins were even originally rather poor in ore. Denudation has most probably carried away such parts of the veins only as were extremely poor to begin with. The structure and mineral association of the investigated veins of the occurrence is uniform to a great extend. Individual deviations are explained by vertical zonality as well as by the differences of the temperature of forma-