The Panagjuri sle ore zone which occupies the central pari of the Srednogorie melall cgm ic zone is known to host two major types of copper deposits formed durirg the Late Crdzccot;s: copper pyrite (volca nog enic) and porphyry copper (pluton cgeni c). The former are of much more varied mineral and met al composition th an the latter. Generally, the two types are quite near each other both in space an d in time of their formation, and in so me cases they are even found together .The Asarel porphyry copper ores occur in secondary quartzites developed in Late Cretaceous medium-acid volcanic an d subvolcanic rocks . The main ore mineral paragenesis is dominated by pyrite and chalcopyrite . It also includes the minerals of polyelemental composition . A lead-zinc mineralization of minor occurrence has been formed later .• At the beginning of the ore-forming process, small oval inclusions of pyrrhotite, chalcopyrite, native gold, ca laverite (?) and bor nite were formed in pyrite. This mineral assembl

The Čiprovci ore zone is known for its polygenic and polychronous mineralizations formed in a siderite-calcite marble bed of Early Paleozoic age. Its general leatures as well as structures, textures and mineral composition record the following events. 1. Deposition of chemogene calcite limestone with hydrothermal-sedimentary siderite interlayers associated with a basic volcanism. Presumable age: Cambrian. 2. Greenschist regional dynamothermal metamorphism that transformed the carbonate rocks into finegrained marbles. Siderite contains 27 ± 5 mol% MnCO3, 6 ± 3 mol% MgCO3 and 1-2 mol% CaCO3. The two kinds of ma1ble are compositionally mosaic due to each grain growing with the composition of its seed carbonate during the metamorphic recrystallization. 3. Formation of a hydrothermal low-temperature silver-lead sulphide mineralization (Pb-Pb model age of 320-340 Ma). It developed metasomatically in the siderite bodies mainly. The hydrothermal fluids were magnesium-rich and their first product was dolomite MgO0.8FeO0.1Mn0.1. They gradually became richer in Fe and Mn supplied during the metasomatic replacement of earlier material, and the dolomite crystals were overgrown by ankerite (up to Fe0.7Mg0.3) and manganian ankerite (up to Fe0.5Mn0.4Mg0.1). Siderite and calcite were redeposited during the later stages of the process. The main characteristics of these metasomatic·carbonate crystals is that they are idiomorphic and compositionally zoned. 4. Formation of syn- and postmagmatic mineralizations associated with a granite intrusion (Pb-Pb model age of 255 ± 17 Ma). Carbonate minerals formed and were transformed during asuccession of processes involving: 1. Thermal metamorphism that converted the siderite marble partly or completely into magnetite ore; 2. Skarn formation in the calcite marbles; and 3. Deposition of a post-skarn oxide-sulphide-arsenide high to medium-temperature mineralization. During the magnetite fo rmation, the fluids were enriched in manganese and magnesium solutes: (Fe, Mn. Mg)CO3+H2O → Fe3O4+Mn2++Mg2++CO-. They deposited high-temperature zoned Ca-Mg-Fe-rhodochrosite, Fe-Mn-magnesite and Mg-Mn-sideritc with end members Mn0.6Fe0.2Ca0.1 Mg0.1 and Mg0.5,Fe0.3,Mn0.2. The rhodochrosite-magnesite solid-solution interval shows a solubility gap observable even on areas smaller than 1 mm2. The end of the process produced also ankerites part of which show high manganese contents (reaching kutnahorite compositions Mn0.5Fe0.3Mg0.2). Formation of a quartz-barite mineralisat ion (Late Cretaceous?). The earlier carbonates were partly redeposited or recrystallized.