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

Trace elements of old sphalerite are Ba, As, Sb, Pb, Ag, Cu, Cd, Sn, Bi, Ti, Mn. Beside these, the young generation contains also gold (spectral analysis results by I. Kubovics). It is interesting to note that although sphalerite sometimes carries significant amounts of cadmium (0,5 per cent in dark, 0,37 per cent in light sphalerite), no cadmium mineral is known from the occurrence. The future discovery of greenockite is to be expected. The presence of wurtzite was recognized by S. Koc h, in connection with the study of the Károly vein. It was later demonstrated by the present author in the Arany Péter vein, too. It occurs generally in the central parts of the veins, in the form of veinlets whose thickness may reach 5 centimetres. The veinlets consist of parallel arrays of thin needle-shaped wurtzite crystals. Aggregates of needles forming half-spheres are also quite frequent, sometimes growing around remnants of old sphalerite. Wurtzite often forms oriented intergrowths with chalcopyrite. In these cases the chalcopyrite grains, arranged in small rows, are oriented parallel or perpendicular to the long axis of wurtzite. Chalcopyrite also occurs in the form of digested rags in the interior of wurtzite. As mentioned above, it occurs exclusively in the Károly and Arany Péter veins, but there it is quite significant. A trace element content of As, Sb, Pb, Ag, Cu, Cd, Sn, Mn was demonstrated spectroscopically by I. Kubovics. Stannite occupies some of the fissures of the young chalcopyrite veins, filling, in their turn, the fissures of old sphalerite. Under the microscope it is a grey mineral of weak réfringence, with no observable pleochroism. Between crossed niçois it exhibits some birefringence. The Sn content of dark sphalerite is due to this mineral. Of the complex sulphides occurring enclosed in the main ore minerals, especially in young galena, bournonite is most frequent. It occurs in smaller amounts in old sphalerite, too. Its colour is much resembling that of galena, may, however, be distinguished by its weaker refrigence. It invariably shows very close-spaced polylamellar twinning according to the (110) face. In most cases it is found in the corners and apices of the galena crystal forming thin needles or isometric grains. It is found in the Arany Péter, Aranybányabérc and Károly veins, whereas none was encountered in the rest. This mineral is responsible for the Sb content of young galena. Tetrahedrite is very rare. The author has demonstrated it from the maingallery level of the Károly vein, from the "2510" and Arany Péter veins. It forms very small (0,01 millimetre) grains in young galena and sphalerite, mostly along the border of the latter, thus it is considered a simultaneous formation. The small amount of As found in the main minerals is presumably derived from tetrahedrite. Arsenopyrite is rather scarce. Up to now it was encountered in the Károly and Arany Péter veins. Its minute crystals exhibit the (110), and (014) planes. It was formed after the main minerals. Its thin needle-shaped crystals form small radial aggregates in the gangue between the main ore minerals. The surface of the crystals is altered. The altered parts show a red internal reflex under the microscope. The nature of the alteration product could not be determined from the small amounts available. Of the complex sulphides jarnesonite, semseyite and boulangerite are known beside bournonite. These minerals are very scarce. Jarnesonite occurs in long thin needle-shaped grains on the surface of the galena grains, sometimes resembling an incrustation. — The réfringence and interference of some very