Inorganic arsenic (As) is a naturally occurring metal, present in various ecosystems. However, it can also be added to an aquatic system by anthropogenic activities. The aim of the present study is to determine the total As content in the Palea Kavala river (NE Macedonia, Northern Greece). The correlation between As content and some chemical and physico-chemical parameters of the samples was also examined. Research demonstrated significant As concentrations in the water and the sediments of the river. No correlation was found between As and pH, Fe, Mn in the water samples. Concerning the sediment samples, positive correlation was revealed for As with Fe and Mn content, while negative correlation was revealed between As and pH. This is probably indicative of a higher arsenic mobility in the Palea Kavala river water than in sediments. Since no anthropogenic activities were observed in the river’s catchment area, elevated As concentrations are probably due to the lithology of the broader area and especially the presence of extended ore mineralizations including As-bearing sulphide minerals. However, the research in the study area is in progress since a more detailed evaluation of the local sources of As and mechanisms of As release is required.

The Kassiteres-Sappes district represents a multi-centered, porphyry-epithermal system developed during the Oligocene to Miocene at a composite calc-alkaline to high-K calc-alkaline volcanic edifice. Precious and base metal mineralization postdates the emplacement of dacite and rhyolite porphyries and is partly superimposed on earlier microdiorite-related porphyry-style mineralization exposed at the Koryfes Hill prospect. A second mineralized porphyry-type system genetically related to a dacite porphyry body developed near the St Demetrios deposit. Tellurides occur mainly at the St Barbara prospect and the St Demetrios deposit. Based on petrographic, electron microprobe, and scanning electron microscope analyses, hessite, petzite, sylvanite, altaite, stützite and native tellurium occur in the St Barbara prospect. These tellurium-bearing minerals are hosted in intermediate-sulfidation type veins and accompanied by pyrite, chalcopyrite, tetrahedrite-group minerals, galena and native gold/electrum. The St Demetrios mineralization includes hessite, altaite, stützite, and tetradymite in close spatial relation to a high-sulfidation assemblage composed of enargite, chalcopyrite, goldfieldite, and native gold. Tellurides were deposited at logfTe2 values of −8.5 to −7.1 and logfS2 values of −10.7 to −7.9 (275 °C). The ore systems are characterized by Au, Ag, Te, Bi, and Mo, which suggests a magmatic contribution to the mineralizing fluids. Ore-forming components were likely derived from both the dacite and rhyolite porphyries.

Mining activities in Kirki ore deposit took place for a short period, from 1975 to1980 and 1990 to 1995. However, the waste piles and the remaining material of the floatation plant have become a significant source of large amount of toxic metals dispersed in the surrounding area. The dangerous wastes contain large amount of unexploited metal-concentrate and toxic chemicals from the former floatation plant (also a number of containers with unused sodium cyanide). All this toxic material is continuously transferred by the rainwater to the river Erini. This river discharges into Aegean sea at a distance of 23 km, on the east coast of Alexandroupolis town. The concentration level of the toxic metals such as Pb, Cu, Zn, As and Cd in the sediments of the river bed is 1140, 50, 290, 100 and 690 times over the stipulated standards.

The penological, mineralogical and geochemical study of tertiary volcanic rocks from Petrota Graben/Maronia, resulted in the distinction of the following pétrographie groups: a) a high-K calcalkaline group (andesites-dacites), b) a shoshonitic group (shoshonitic andésites, trachytic lavas, c) rhyodacitic ignimbrites and ignimbritic tuffs with high-K calc-alkaline to shoshonitic affinity, and d) rhyolites. The shoshonitic volcanic rocks and the rhyolites are probably originated from the neighbouring Maronia plutonio complex. In addition the calc-alkaline group is related to similar volcanics outcroping in the Mesti-Kassiteres area (the northeastern extension of the Graben). The petrogenesis of the volcanic rocks of the Petrota gragen is attibuted to fractional crystallization and/or magma mixing processes. Epithermal style mineralizations in Mavrokoryfi, Perama Hill and Odontoto are believed to be genetically related to the rhyolitic magmatism in the area.

In this study a new occurrence of Pb-rich members of the alunite supergroup minerals is described. The "alunites" were traced in advanced argilic alteration zones of epithermal and porphyry type mineralizations in W. Thrace/(Greece). These "alunites" are Ca-Sr-Ba-Pb-rich phosphatessulfates and represent solid solutions between members of the alunite, woodhouseite and crandallite group minerals. The highest concentrations of PbO in the Mavrokoryfi and Melitaina alunites are 24.7% and 17.4% respectively. The plumbian phosphates-sulfates occur in the cores of the crystals and are surrounded by common K-Na-rich alunites in Mavrokoryfi and Ba-rich woodhouseite in Melitena, an indication that they were formed in a magmatic-hydrothermal environment after dissolution of apatite and feldspars by phosphate-sulphate rich solutions. The mineral-chemistry of these "alunites" can provide information regarding the genesis of the advanced argilic alteration zones in Greece, and help us in the distinction of the epithermal from deep porphyry style environments.

Quartz-carbonate-base metal veins in the Pagoni Rachi and Kassiteres Cu-(+/-Mo) prospects represent late-stage mineralising events depositing base metal sulfides, sulfosalts and tellurides. These veins are telescoped upon earlier magmatic-hydrothermal veins and associated K-silicate alteration of the subvolcanic dacitic andesite and diorite hostrocks. Element microprobe analysis are used to identify chemical variation of tetrahedrite series minerals, sphalerite and galena. A "stuetzite" similar Ag-telluride was for the first time recorded in the Pagoni Rachi porphyry system. Preliminary microthermometric data revealed that late-stage veins were deposited by intermediate temperatured fluids (250degrees and 300degreesC) at low salinities (1.4 - 2.7 wt.% NaCl equiv.), indicating strong partitioning of meteoric fluids in the systems. The intermediate-sulphidation (IS) character of the base metal veins, is compared to neighbouring high-sulphidation (HS) mineralisations.

Significant porphyry-Cu-Mo and epithermal Au-Ag-Cu deposits occur in the Tertiary Rhodope metallogenic province in Greece. The porphyry-type deposits are related to quartz stockworks developed in K-silicate and sericitic-altered intermediate (andesitic, dioritic) to acid (dacitic, microgranitic) porphyry stocks. The epithermal mineralisation is dominated by high-sulphidation types, which are characterised by ore deposition in hydrothermal breccias and veins within previously advanced argillic-altered subvolcanic and volcanic rocks. In Kassiteres-Sapes area the high-sulphidation mineralisation is overprinted by intermediate sulphidation epithermal quartz veins, suggesting the presence of two distinctively different fluids within the same system. Almost all of the studied epithermal deposits in Thrace are considered to be related to porphyry systems. Late acid magmatism played a major role in supplying the epithermal systems with volatiles and metals.

The Au-Ag-Cu mineralisation in the Paliomylos area is associated with quartz segregations and pegmatoids in the form of boudinaged bodies. The Au, Ag and Cu contents in the ore bodies reach 6.8 ppm, 765 ppm and 0.80 wt%. The ore minerals consist of pyrite, chalcopyrite, sphalerite, pyrrhotite, galena, bismuthinite, argentopentlandite, gersdorffite, cobaltite, aikinite, hessite, native bismuth and gold. Pentlandite contains significant amounts in Ag (13.15 wt%), Au (1.59 wt%) and PGM, demonstrating a formula of Fe5.37 Ni2.56 Ag1.03 Ir0.03 S8.01. On the basis of geological, textural and chemical data, the mineralisation in the studied area was formed under high temperatures.

The present study correlates both the mineralogy of the hydrothermal alteration and the mineral chemistry of molybdenites from three porphyry Mo ± Cu occurrences in Thrace: Melitena, Pagoni Rachi/Kirki and Ktismata/ Maronia. The mineralisations are genetically related to calcalkaline, subvolcanic bodies of Tertiary age. According to their mineralogical and chemical composition the host rocks are characterized as dacite (Melitena), dacitic andésite (Pagoni Rachi) and porphyry microgranite (Ktismata/Maronia). The molybdenites occur in disseminated form, as fracture fillings, as well within quartz stockworks crosscuting the central alteration zones of the intrusives. They are accompanied by the following mineral assemblages: quartz, sericite, pyrophyllite, diaspore, Ca-Ba-rich alunite, pyrite (Melitena); quartz, albite/K-feldspar, biotite, actinolite, magnetite (Pagoni Rachi); and sericite, kaolinite, pyrophyllite, chlorite (Ktismata). Preliminary microthermometric results showed homogenisation temperatures from 352° to 390 °C for Pagoni Rachi area and from 295° to 363 °C for Melitena area. The salinities range between 4.5 and 6.1 wt% eq. NaCl and between 2.7 and 3.4 wt% eq. NaCl, respectively. Detailed study on over 400 fluid inclusions from the porphyry Cu-Mo deposit in Maronia area revealed formation temperatures from 300° to 420 °C, whereas salinities are distincted in two different groups from 6 to 16 wt% eq. NaCl and from 28 to 55 wt% eq. NaCl. The chemical composition of the molybdenites from the three porphyry Mo±Cu deposits in Thrace was studied with 155 microprobe analyses. The results revealed unusual high and variable Re concentrations in the studied molybdenites. Re content in molybdenite from Melitena area vary from 0.21 to 1.74 wt%, 0.79 wt% on average. The highest values were measured in samples from Pagoni Rachi (0.45-4.21 wt%, 1.98 wt% on average). Finally, microprobe analyses from molybdenite in Ktismata/Maronia showed Re content between 0.12 and 2.88 wt% (0.76 wt% on average). Rhenium is a very rare element with many definite uses, and is mainly associated with molybdenite in porphyry type deposits. According to the data published so far the Re content in molybdenite reaches up to 0.42 wt%. It is obvious therefore that such high Re concentrations (0.12 to 4.22 wt%) from the studied molybdenites in Thrace, are very ineresting for a possible future exploitation.

The SE part of Attica belong to the Attico Cycladic massif and comprises gneiss, quartzites series of marble and scists, metabasites and metaultrabasites. The metabasites (prasinittes) of Laurium area recognized in over 60 outcrops. The main mineral of the metabasites are actinolites, actinolitic hornblende glaucophan frequently altered to chlorite, albite, epidot - clinozoisite and chlorite which in the most frequent mineral. According to the mineral composition those metabasites have been affected by an intermediate to high temperature green - schist metamorphic phase. Nevertheless the presence of glaucophane shows that a high pressure metamorphic phase under subduction conditions was preceded. The detailed study of distinctive classification diagrams based on the main and trace elements of the Laurium prassinites showed a subalkalic basaltic character. The geotectonic environment of thoss basaltic magmas should be of MORB type with a tholeiitic character belonging the E or PMORB type basalts

Exploration in the southern part of Western Thrace has resulted in the discovery of target areas for epithermal gold-silver mineralization, hosted in Tertiary sediments and Oligocene intermediate to acid volcanic rocks. The low-sulfidation type mineralization (Perma Hill prospect), which by tonnage and gold grade is considered as a promising target, is associated with veins and stockworks crosscuting a zone of vuggy and massive silicification of Eocene sandstones, A high-sulfidation mineralization (Mavrokoryfi prospect) is hosted within veins of black massive silicification, which grade upwards to opal-bearing silicification of andesitic rocks. Fluid inclusion measurements from the Perama Hill prospect indicate deposition of the silicic alteration zone from a hydrothermal fluid at temperatures around 185 degrees C with salinities 5.5 to 5.7 equiv. wt% NaCl, probably as a result of mixing of boiling hydrothermal fluids with descending steam-heated waters. Precious metals in the quartz-barite veins were introduced by hydrothermal fluids of similar temperatures characterized by lower salinities.

The morphology and the chemical composition of placer gold grains in Marathousa area are studied for the first time. The auriferous sediments contain up to 4.20 ppm gold. The decrease in the Ag contents of the gold grains from the up-to the downstream is attributed to the 20 km transport. Concerning the origin of the studied placer gold, various sources can be suggested, a fact which is of great importance for future exploitation.

Eine hochthermale Alteration führte zur Bleichung und zu starken chemischen Veränderungen des Gesteins, das durch Albitisierung, Serizitisierung und Verkieselung gekennzeichnet ist. Hiermit ist eine Erzmineralisation des “porphyry-Typs” aus Molybdänit, Kupferkies und Pyrit verbunden. Um das gebleichte Gestein ist der dazitische Andesit propylitisiert. In diesem Umwandlungsstadium treten Chlorit, Epidot, Karbonate, Prehnit und Zeolith auf.