CHEMISTRY AND MORPHOLOGY OF ZIRCON IN METAGRANITES FROM MALESHEVSKA AND OGRAZHDEN MOUNTAINS, SMM, SW BULGARIA R. TITORENKOVA and L. MACHEVA Central Laboratory of Mineralogy and Crystallography, BAS, ul. Acad. G. Bonchev, bl.107, 1113 Sofia, Bulgaria; rosititorenkova@dir.bg Abstract: External morphology, inner structure and chemical composition of zircon crystals from high-grade quartz-feldspar gneisses from the Bulgarian part of SMM are studied. These data confirm the magmatic origin of the protolithes and trace back their evolutional trend during consecutive stages of crystallization and alteration. Keywords: Back-scattered electron (BSE), Cathodoluminescence (CL), Metamorphism, Serbo- Macedonian Massif, Zircon, Zonality. Introduction The stability of zircon in most geological processes, its low solubility and low elemental diffusion enables it to survive almost any crustal processes and make it a suitable mineral in studying metamorphic terrains with complex polyphase evolution. It is proposed that a complex investigations on zircon - external morphology, inner structure and chemical composition of the major and trace elements to could give valuable information on the main stages of metamorphism and deformation. In this reason we try to apply zircon peculiarities to clarify some unresolved questions, coupled with the nature of the protolithes of the metamorphic rocks from the Maleshevska and Ograzhden Mnts., SW Bulgaria and their geological evolution. Geological setting The metamorphic rocks from the most southeastern part of Serbo-Macedonian Massif (SMM), SW Bulgaria, were studied. They belong to the Maleshevska and Belasishka groups of the Ograzhdenian complex (Zagorchev, 1988) and are present mainly by high- grade gneisses, migmatites, amphibolites and metapelites. The current field and petrological investigations of quartz-feldspatic gneisses proved the magmatic origin of the main part of these rocks, participating in different nape structures. Two types of metagranites have been distinguished: one with equigranular structure, and another