Dr. Nagy I. Zoltán szerk.: Fragmenta Mineralogica Et Palaentologica 3. 1972. (Budapest, 1972)

the great abundance of granite porphyry, aplite and quarz dikes. Consequently the probability of such a hybridization process could have been great. The 2V^ frequency distribution of orthoclase crystals showing two maxima confirms this supposition. The subhedral crystals of orthoclase with greater 2V^ values might have begun to develop in the granitic magma, while the anhedral ones having "sanidine" optic began to crystallize only after the intrusion of the dikes had taken place

.Supposing a fairly intense hybridization process, the more granitic composition of the Csala Forest and Székesfehérvár Quarry dike can well be explained. With increasing K-content more and more biotite develops instead of hornblende in these dikes and the amount of quartz and that of orthoclase increases at the same time. The fact that the composition became more granitic is shown in Figure 4. The values representing the composition of the dikes and that of the Velence granite lie along a straight line. Acknowledgement The author wishes to thank Professor K. I. Sztrókay for his critical review of the manuscript. A Velencei-hegység lamprofiros kőzeteinek vizsgálata Embey-Isztin Antal Természettudományi Múzeum Asvány-Kőzettára, Budapest Összefoglalás. - Hungarian summary. A Velencei hegységben három helyről irtak le bázisos, lamprofiros jellegű telérkőzetet: a Sárhegy csúcsától DK-re, a Csalai