Kaszab Zoltán (szerk.): A Magyar Természettudományi Múzeum évkönyve 70. (Budapest 1978)

Noske-Fazekas, G. ; Embey-Isztin, A.: New data to the mineralogy of the basic intrusion around the village Szarvaskő, Hungary

parallel to their t-axes. Uralitization of the diallage is widespread (Plate II Fig. 1). In addition to the diallage a very few augite and hyperstene are also present. In contrast to the Tóbércbánya gabbro, in the Tardosbánya one there is only a small amount of amphibole (Table 1). The brown amphibole is strongly pleochroic and forms anhedral crystals among other constituents. Chloritization in the marginal parts of the amphibole is widespread (Plate II: 2). There is a minor amount of biotite which is altered partly to chlorite and partly to a colourless mica. The amount of opaque minerals is significant in the gabbro of Tardosbánya. A smaller part of these are sulphides, pyrite and chalcopyrite: the rest is ilmenite and magnetite according to SZENTPÉTERY (1953). The irregularly shaped opaque minerals typically occur in the vicinity of alteration zones of mafic silicate minerals (Plate III: 1). This strongly suggests that they are also alteration products of some hydrothermal process. In contrast the subhedral isometric crystals of magnetite and ilmenite in the wehrlite of Vasbányahegy may have originated by some cumulus process (Plate III : 2). Among the accessories the euhedral grains of apatite (100-300 [i.) are the most important. Macroscopically the rock of Tóbércbánya is similar to the gabbro of Tardosbánya, but microscopically there are several differences. The former rock is less intensively altered and contains much less amounts of opaque minerals, especially the sulphide ores become insignificant. Its colour index is slightly lower. The laths of plagioclase are more elongated, generally they form polysynthetic twin crystals. Carbonitization of the feldspar is not rare. In some of the plagioclase grains there is a nucleus with Fig. 1, Outline map of the basic intrusion around Szarvaskő according to SZENTPÉTERY (1953). —Key: 1 = diabase, 2 = gabbro, 3 = ore-peridotite, 4 = sediment