Thomas Kerestedjian

• Professor, PhD
• Head of Department at Bulgarian Academy of Sciences

Oxygen-bearing platinum group minerals (O-bearing PGMs) are intergrown with base metal sulfides (BMS, e.g., pentlandite–[NiFe]9S8) within fractures in chromite grains from chromitite bodies on Ouen Island, New Caledonia. These PGMs are hosted in chlorite and serpentine, which formed during serpentinization of olivine and pyroxene. The O-bearing PGM...

One of the goals of the study is to establish the conditions that affect the water quality in the catchment area of the Mesta River (Southwest Bulgaria). This will help to distinguish the anthropogenic impact from natural factors, with geological setting in first place. For the formation of the chemical composition of the waters in regional aspect,...

This is an open access article under the CC BY-NC-SA license(https://creativecommons.org/licenses/by-nc-sa/4.0/) RESUMEN Rocas del manto superior ofiolitico tales como peridotitas y cromititas contienen esfe-ras. Estas consisten de: (1) hierro native con cantidades variables de Ni con y sin inclu-siones de vidrio silicatdo y óxidos (wüstite), (2) i...

The raw materials obtained from the Earth’s crust (Geomaterials) are of fundamental importance for a wide range of industries [...]

The Rietveld method using X-ray powder diffraction data was applied to selected skarn samples for quantitative determination of the present minerals. The specimens include garnet, clinopyroxene–garnet, plagioclase–clinopyroxene–wollastonite–garnet, plagioclase–clinopyroxene–wollastonite, plagioclase–clinopyroxene–wollastonite–epidote, and plagiocla...

Porphyry Cu can contain significant concentrations of platinum-group elements (PGE: Os, Ir, Ru, Rh, Pt, Pd). In this study, we provide a comprehensive in situ analysis of noble metals (PGE, Au, Ag) for (Cu-Fe)-rich sulfides from the Elatsite, one of the world’s PGE-richest porphyry Cu deposits. These data, acquired using laser ablation-inductively...

The present study demonstrates the capabilities of the Rietveld procedure to track the structural transformations and framework flexibility on the example of the natural water-containing zirconosilicate elpidite, subjected (in bulk) to thermal treatment from room temperature to 300 °C. The methodological approach to the performed refinements and th...

The alteration of chromian spinel is a key process during serpentinization and metamorphism of ultramafic rocks controlled by oxygen fugacity (fO2) and Fe²⁺ ↔ Fe³⁺ exchange during fluid–rock interaction. Chromian spinel alteration is better recorded in less permeable chromitite than in peridotites where extensive fluid–rock interaction frequently o...

The dehydration-rehydration processes of three Zn-hydroxy sulfate minerals with interrupted decorated sheet structures – osakaite, gordaite and Ca-gordaite were investigated. The obtained products and processes were characterized by DTA-TG-MS, in situ and ex situ PXRD and FTIR.

The study presents the results of a decade-long investigation of the environmental status in the area of the KCM smelter (Plovdiv, Bulgaria). All pollution sources, pathways and targets in the area are recognized and their roles in the overall environmental status are evaluated. The range and direction of seasonal dynamics of all analyzed factors i...

Chromites in high-Al and high-Cr chromitites from the ultramafic massifs of Golyamo Kamenyane and Jakovitsa (Bulgaria) preserve four types of microstructures: i) partly-altered chromite, with primary cores surrounded by porous chromite enriched in Cr and Fe 2+ and depleted in Al and Mg; ii) porous chromite, with chlorite in the pores; iii) zoned ch...

Chemical signatures of chromitites are commonly used to track the evolution of Earth’s mantle. However, chemical modification during deformation may have important implications for the interpretation of chromites’ signatures. Here, we describe the details of how deformation promotes chemical modification in chromite. Physicochemical characteristics...

The effect of pH on the kinetics of tremolite and anthophyllite dissolution was investigated at 25°C in batch reactors over the pH range of 1 to 13.5, in inorganic buffered solutions. Dissolution rates were obtained based on the release of Si and Mg. Results obtained in this study show different behaviors for both minerals. For tremolite, dissoluti...

A two-stage mechanism associated with the infiltration of fluids during retrograde metsamorphism from eclogite to amphibolite facies in the ultramafic massif of Golyamo Kamenyane (Bulgaria) has produced four types of microstructures in chromites: i) porous chromite, with chlorite in the pores, ii) non-porous chromite, iii) partly altered chromite,...

Podiform chromitites occur in the meta-dunite horizon of the Dobromirtsi ultramafic massif, in the Central Rhodope metamorphic core complex (southern Bulgaria). Although these were deformed and metamorphosed together with their host rocks several chromite cores from massive chromitite samples still preserve compositions unaffected by metamorphism -...

In the Eastern Rhodopes (SE Bulgaria) the low-Al and low-Ti chromite forming chromitite bodies at Yakovitsa and Avren West massifs, and the high-Al and variable Ti chromite forming chromitite bodies at Golyamo Kamenyane (low-Ti) and Chernichevo (high-Ti) occur hosted within a representative ophiolitic mantle sequence formed in a mid-oceanic ridge,...

The Golyamo Kamenyane serpentinite is a por-tion of a metaophiolite, located in the Upper High-Grade Unit of the metamorphic basement of the Eastern Rhodope Metamorphic Complex, SE Bulgaria. It consists of meta-harzburgite and metadunite hosting layers of metagabbro and some chromitite bodies. All these lithologies were affected by ultrahigh-pressu...

Chemical variations of chromite from several different-size chromitite bodies in metamorphosed ophiolites from Kosturino (Rhodope Mountains, SE Bulgaria) show that metamorphic alteration took place in an open system, in three separate stages: 1) subsolidus equilibration of chromite with olivine, 2) mass loss of chromite under reducing conditions an...

The Os-isotope compositions of platinum-group minerals (PGMs) in ophiolite chromitites are commonly regarded as resistant to fl uid-related processes, and have been used to track the evolution of Earth’s convecting mantle. However, we have found signifi cant differences in 187Os/188Os between primary and secondary PGMs from metamorphosed ophiolite...

A number of asbestos mines in the Rhodope Mountains , SE Bulgaria, were extensively exploited for an-thophyllite asbestos in the middle of the 20th century. After the late 70-ies, when mining was discontinued for safety regulation reasons, a large number of unsecured asbestos dumps was left behind. These dumps are currently very hazardous, because...

Along with its normal (flat sample) mode, the unique for Bulgaria Guinier image foil camera in the Geological Institute (Bulgarian Academy of Sciences) can also be used in capillary mode. In this mode a dedicated ceramic heater can be attached, so that the whole setup is turned into a powerful thermal device. The possible uses of this device are nu...

The Dobromirtsi Ultramafic Massif, located in the Rhodope Mountains (SE Bulgaria), is a portion of a Paleozoic sub-oceanic mantle affected by polyphase regional metamorphism. This massif contains several small, podiform chromitite bodies which underwent the same metamorphic evolution as their host peridotites. Like other ophiolite chromitites, thos...

The Dobromirtsi Ultramafic Massif, located in the Rhodope Mountains (SE Bulgaria), is a portion of a Paleozoic sub-oceanic mantle affected by polyphase regional metamorphism. This massif contains several small, podiform chromitite bodies which underwent the same metamorphic evolution as their host peridotites. Like other ophiolite chromitites, thos...

This paper reviews the distribution of platinum-group minerals in ophiolitic chromitites. Our data and literature data, obtained by in-situ investigation of polished sections and techniques of mechanical separation [hydroseparation (HS), or combining electric pulse disaggregation (EPD) plus HS], are contrasted. Finally, in-situ textural data are us...

We have investigated several chromite deposits in the Mayarı´-Baracoa Ophiolite Belt (eastern Cuba) and in the Dobromirtsi metamorphosed ultramafic (ophiolitic) massif (SE Bulgaria) with regard to zoning in platinum-group minerals (PGM) of the laurite (RuS2)–erlichmanite (OsS2) solid solution series. We found several zoned laurite–erlichmanite grai...

Alteration processes in the waste dumps of the KCM non-ferrous metal smelter near Plovdiv and their environmental impact have been focussed in this study. The waste materials from the metallurgical production (weltz-clinker) expected to be relatively insoluble were found to be affected by spontaneously initiated burning processes, turning the chemi...

Podiform chromitite bodies occur in highly serpentinized peridotites at Dobromirtsi Ultramafic Massif (Rhodope Mountains, southeastern Bulgaria). The ultramafic body is believed to represent a fragment of Palaeozoic ophiolite mantle. The ophiolite sequence is associated with greenschist-lower-temperature amphi-bolite facies metamorphosed rocks (bio...

In the almost 5000 years long history of Georgia metallurgy has always played an important role. Its specifics, development, ups and downs and new reincarnations in other times and places, over and over again are the main story in this paper. Southern Georgian metallurgical centres are considered the birth place of the iron metallurgy of the world...

Tetrahedrite-tennantite fahlores and minerals of the polybasite-pearceite series from the Chiprovtsi Ag-Pb deposit (NW Bulgaria) have been studied by reflected light microscopy and electron microprobe analysis. The microprobe analyses revealed a wide variety of compositions within the fahlore solid solution series, regarding Ag, Zn, Fe and Cd conte...

A cinnabar-pyrite mineralization is found within the fluorite replacement bodies in the eastern part of the Chiprovtsi silver-lead deposit. The mineralization has simple composition comprising pyrite, cinnabar and smaller amounts of metacinnabar, marcasite, galena, chalcopyrite and minerals of the tetrahedrite-tennantite and polybasite-pearceite se...

Godlevskite Ni9S8 is recorded for the first time in Bulgaria. The find comes from chromitites in serpentinized ultramafics (dunites, peridotites), near the village of Dobromirtsi, Central Rhodopes. The postmagmatic assemblage of the chromitites comprises pentlandite, godlevskite, heazlewoodite, maucherite, orcelite, chalcopyrite and gersdorffite (i...

Chiprovtsi silver-lead and Martinovo iron mines represent the biggest mining area in Northwestern Bulgaria, which was operated till 1999. Their long-lived operation leads to proved pollution of the environment in the vicinity of the mines, especially water and soil. Seasonal monitoring of heavy metal (Cu, Zn, Cd and Pb) and metalloid (As and Sb) co...

Rare bismuth minerals were found in the postskarn sulphide-arsenide mineralization in the Martinovo iron deposit, Northwestern Bulgaria. The postskarn mineralization has direct relation to the Sveti Nikola collisional granite intrusion into the rocks of the Diabase Phyllitoid Complex. The observed bismuth minerals spatially associate with the pyrrh...

Signiicant shifting of the microbial communities structure was detected in three metal-polluted soils collected around the Pb-Zn smeltery KCM and the agrochemical factory AGRIA situated near the town of Plovdiv, Bulgaria. Industrial-, dumpsite-and agricultural soils were contaminated with As: 7.5-52.9 mg/kg; Hg: 0.086-0.404 mg/kg; Cd: 2.3-71.1 mg/k...

ABSTRACT A number of Paleozoic gold deposits are situated in the Hercynian terrains of the Balkan Mountain. On Bulgarian territory Govezhda and Svishti Plaz deposits are the most important ones. Neresnitza, Blagoev-Kamen and Osanitza deposits are located in the Serbian part of the Balkan Mountain. All these deposits are hosted in the Pre-Alpine bas...

The Govezhda gold deposit is situated in the Western Balkan Mountains, NW Bulgaria. It has been operating during the 1961-1992 period, but the mineralization remains not completely well known. Four mineralization stages, reflecting the following geochemical trend are defined: Fe-As-Au; Pb-Zn-Cu-Ag-Au: Ag-Pb-Cu-Sb; Ca. (1) The products of the first...

Soil and water samples picked around the biggest Pb-Zn smelter in Bulgaria were investigated. The qualitative and quantitative analyses showed abundance of heterotrophic aerobes and spore forming bacteria. Mn (IV)-reducing, Fe(III)-reducing and sulphate-reducing bacteria were very well represented. The genus Thiobacillus as well as fungi and actino...

The Late Cretaceous Silistar intrusion comprises of gabbros, gabbro-diorites to quartz-diorites and aplites, that were emplaced into a volcano-sedimentary succession of similar age. Structural data suggest that this intrusion is part of a larger, partially exposed body. A dense network of primary and secondary joints, in many places filled with var...

Native gold is an important economic component of the complex ores of the Chelopech high-sulphidation volcanic-hosted epithermal Au-Cu deposit (Bulgaria). The ore consists of pyrite, chalcedonic silica, chalcopyrite, enargite, luzonite, tennantite, bornite, sphalerite, galena, and numerous other sulphide, arsenide and telluride minerals. Gold is pa...

A complex bismuthiferous association is found in the Svishti Plaz gold deposit situated in Central Balkan Mountain. The vein type mineralization is hosted in Paleozoic dioritic, granodioritic and quartz-dioritic plutonic bodies and related hornfelses. The ore consists of arsenopyrite, pyrite, native gold, galena, sphalerite, tennantite, pyrrhotite,...

Chemical sector zoning is an almost universal feature in arsenopyrite. The present study reveals distinct relations between different crystal area compositions on both the qualitative and quantitative levels. Composition-morphology dependencies are also established. As far as these features reflect environmental conditions during crystal growth, th...

Forty years of ore processing in the Chiprovtsi region have produced voluminous fines dumped at the Mechi Dol and Golyam Bukovets tailings ponds. The original ores are of three types; magnetite from Martinovo, silver-bearing galena and other sulphides from Chiprovtsi, and gold-sulphide quartz veins from the nearby area of Govezhda. The Mechi Dol po...

A simple quartz-arsenopyrite vein assemblage formed at temperatures of 280-200-degrees-C occurs in the Madan lead-zinc ore district, Bulgaria. Spear-shaped arsenopyrite is bounded by {101}, {010} and {210}; compositionally it is pure FeAs1-xS1+x of variable x. The BSE image of an oriented (001) section reveals a pronounced sector zoning defined sol...

The study represents the results of an extended study of the main geoecological components of the environment. The study combines direct investigations and an exhausting review of the existing geological information. The results are represented as a set of maps with their respective explanatory notes as follows: map of the natural hydrogeological c...