Ferenc Lázár Forray

Babeş-Bolyai University | UBB · Department of Geology

The enthalpy of formation from the elements of a well-characterized synthetic Pb-jarosite sample corresponding to the chemical formula (H3O)0.74Pb0.13Fe2.92(SO4)2(OH)5.76(H2O)0.24 was measured by high temperature oxide melt solution calorimetry. This value (DH f = 3695.9 ± 9.7 kJ/mol) is the first direct measurement of the heat of formation for a l...

Yavapaiite, KFe(SO4)2, is a rare mineral in nature, but its structure is considered as a reference for many synthetic compounds in the alum supergroup. Several authors mention the formation of yavapaiite by heating potassium jarosite above ca. 400°C. To understand the thermal decomposition of jarosite, thermodynamic data for phases in the K-Fe-S-O-...

The enthalpy of formation from the elements of well characterized Pb–As, Pb–Cu, and Pb–Zn synthetic jarosites, corresponding to chemical formulas (H3O)0.68±0.03Pb0.32±0.002Fe2.86±0.14(SO4)1.69±0.08(AsO4)0.31±0.02(OH)5.59±0.28(H2O)0.41±0.02, (H3O)0.67±0.03Pb0.33±0.02Fe2.71±0.14Cu0.25±0.01(SO4)2±0.00(OH)5.96±0.30(H2O)0.04±0.002 and (H3O)0.57±0.03Pb0....

Jarosite, a potassium (sodium) iron sulphate hydrated mineral, has recently been identified on the martian surface by the Opportunity rover. Using recent thermochemical data [Drouet and Navrotsky, 2003, Geochim. Cosmochim. Acta 67, 2063–2076; Forray et al., 2005, Geochim. Cosmochim. Acta, in press], we calculate the equilibrium decomposition curve...

The present study performs an extensive survey of the radioactive properties of carbonated spring waters from the post-volcanic area of Harghita county, Romania. Gross alpha activities ranged from 0.018 to 1.941 Bq/L, with ~ 46% of the samples presenting values over the parametric value established by the Romanian law, while only ~ 10.5% were above...

This study describes mineralogical and crystallochemical characteristics of metamorphic tourmalines from an Alpine shear zone in a Variscan metamorphic rock sequence from the Maramures region in the northern part of the East Carpathians. We use this mineral to unravel aspects of the evolution of the tourmaline bearing host rocks and compare the cry...

The Apuseni Mountains are located between the large geothermal area of the Pannonian Basin and the low thermal flux Transylvanian Basin. Thermal and mineral waters have been sampled from 42 points along a NW-SE transect. The general chemistry and the water isotope (deuterium and oxygen-18) composition were analyzed. Most of the thermal aquifers are...

In this study, we describe a sedimentary deposit situated above Ascunsă Cave (SW Romania) that should be in depositional connection with coeval stalagmites from the cave. We excavated a 2.5 m deep soil profile and took contiguous bulk samples every 5 cm. Soil samples were analyzed for clay mineralogy, grain size, chemical composition, magnetic susc...

An amendment to this paper has been published and can be accessed via a link at the top of the paper.

A mud volcano (MV) is a naturally hydrocarbon-spiked environment, as indicated by the presence of various quantities of PAHs and aromatic isotopic shifts in its sediments. Recurrent expulsion of various hydrocarbons consolidates the growth of hydrocarbonoclastic bacterial communities in the areas around MVs. In addition to the widely-known availabi...

Exports of dissolved inorganic carbon (DIC) from karst aquifers are a significant contribution to the global carbon cycle. Contributions of particulate inorganic carbon (PIC) and dissolved organic carbon (DOC) in karst groundwater are often unaccounted for in carbon budgets. This investigation considers field chemistry, discrete samples, and contin...

Two cores of bat guano were recovered from Topolnița and Gura Ponicovei Caves in the south-west region of Romania and analyzed for δ ¹⁵ N, δ ¹³ C and pollen. Deposition of guano began in CE 1537 at Gura Ponicovei and CE 1694 at Topolnița, allowing for the development and interpretation of climate and vegetation records since the Little Ice Age. δ ¹...

Despite its modest appearance and relatively difficult to explore fossil section, the underwater part of the Izbândiş system makes this cave special, as it hosts the deepest sump in Romania (−105 m). Besides, archeological findings in this cave had helped understand the spread of the Igriţa-type culture and its distinctive objects. The cave is also...

Zidită Cave distinguishes itself from other caves in the region due to the archaeological artifacts discovered in the sediments accumulated at the cave entrance, the paleoclimatic information recorded in the cave’s sediment, and longtime hibernacula and nursery for several bat species.

A 285‐cm core of bat guano was recovered from Măgurici Cave in north‐west Romania and analyzed for δ¹³C, δ¹⁵N and pollen. Guano deposition occurred from AD 881 until 1240 and from AD 1651 to 2013, allowing for the interpretation of summer variations in precipitation and temperature during the Medieval Warm Period (MWP) and the Little Ice Age (LIA)....

Sulfur Cave (Puturosu Mountain, Romania) is an extreme environment, unique for displaying life in a gas chemocline. The lower part of the cave is filled with CO2, CH4, and H2S of mofettic origin, while the upper part contains air that floats above the heavier volcanic gasses. S° and H2SO4 (from sulfur-oxidation) cover the cave wall at and below the...

δ13C and δ15N analysis was completed on a 285 cm guano deposit found in Măgurici Cave (NW Romania). A hiatus was found in the ~1.2 ka core between AD 1240 to AD 1651 that appears to correspond with the beginning of the Little Ice Age. δ13C values indicate that vegetation was exclusively C3 plants in the region since AD 800, therefore δ13C values of...

We present here the results of a 4-year environmental monitoring program at Ascunsă Cave (southwestern Romania) designed to help us understand how climate information is transferred through the karst system and archived by speleothems. The air temperature inside the cave is around 7 °C, with slight differences between the upper and lower parts of t...

Currently there is a scarcity of paleo-records related to the North Atlantic Oscillation (NAO), particularly in East-Central Europe (ECE). Here we report δ15N analysis of guano from a cave in NW Romania with the intent of reconstructing past variation in ECE hydroclimate and examine NAO impacts on winter precipitation. We argue that the δ15N values...

We present here the results of a four year environmental monitoring program at Ascunsă Cave, Romania, intended to understand how climate information is transferred through the karst system and archived in speleothems. The air temperature inside the cave is around 7 °C, with slight differences between the upper and lower parts of the 20 main passage...

Fewstudies have attributed δ15N values of guano to a factor other than diet. A δ15N record obtained froma 1.5-m core of bat guano deposit from Zidită Cave (western Romania) provides a record of anthropogenic and climatic influence on the regional nitrogen pool. Nitrogen content is nearly constant (%N N 9) for over 1 m of the core, indicating limite...

TThis paper reports the first results on δ18O and δ2H analysis of precipitations, cave drip waters, and groundwaters from sites in Mallorca (Balearic Islands, western Mediterranean), a key region for paleoclimate studies. Understanding the isotopic variability and the sources of moisture in modern climate systems is required to develop speleothem i...

We provide sedimentological, geochemical, mineral magnetic, stable carbon isotope, charcoal, and pollen-based evidence from a guano/clay sequence in Gaura cu Muscă Cave (SW Romania), from which we deduced that from ~ 1230 BC to ~ AD 1240 climate oscillated between wet and dry. From ~ 1230 BC to AD 1000 the climate was wetter than the present, promp...

Lacustrine sediments are excellent sources of palaeoenvironmental and palaeoclimatic information because they usually provide continuous and high-resolution records. In centraleastern Europe however lacustrine records that extend beyond the Holocene are rather sparse.Palaeomagnetic records from this region are also insufficiently explored, and usua...

The δ13C values of 23 unevenly spaced guano samples from a 17-cm long clay sediment profile in Gaura cu Musc ă Cave (GM), in SW Romania, made it possible to preliminarily characterize the Medieval Warm Period summer hydroclimate regime. The beginning of the sequence (AD 990) was rather wet for more than a century, before becoming progressively drie...

The original article has been published inadvertently with some errors in the equation under section Carbon isotope composition and Fig. 2. The corrected equation and Fig. 2 are given below.

Rosia Montana, the largest European gold mine, could be re-opened. Environmental problems led to severe pollution of the Rosia and Abrud Rivers. The two main potentially toxic element (PTE) sources in mine sites are, in general, the abandoned underground workings and the piles of waste rock. Since the composition of waste rocks is often heterogeneo...

For the last 2000 years gold has been mined in the Southern Apuseni Mountains in Romania from both primary (hydrothermal) and secondary (river placer) deposits. The gold-bearing area covers about 900 km2 and represents the richest Au-Ag province in Europe. The ore originating from the Southern Apuseni Mountains is known as ‘‘Transylvanian gold’’. T...

Arsenic represents a major concern for drinking water supplies not only in USA (Ryker, 2003) but also in other countries around the world (Zhang, et al., 2002, Saha, 2003, Bundschuh, et al., 2004). Despite its high toxicity, the available thermodynamic data for arsenic containing minerals are scarce or not well determined (Nordstrom and Archer, 200...

Sulfates have been identified in Martian soils and bedrock and are emerging as an important indicator for aqueous activity on Mars. Sulfate minerals can form in a variety of low-temperature (evaporitic; chemical-weathering) and high-temperature (volcanic/fumarolic; hydrothermal) environments and their formational environments can range from alkalin...

Jarosite, KFe3(SO4)2(OH)6, a hydrated sulfate of iron and potassium is a widespread mineral in nature, mostly connected with alteration of sulfides and present in acid mine drainages [1, 2] or connected with volcanic or postvolcanic activity (alteration of volcanic rocks in acid fumaroles [3, 4], or hydrothermal activity [5]) with or without implic...

The present paper describes a new type of concretions for Romania: loose (non-fixed) hydrothermal concretions with a central void, a mineralogenetic curiosity from the Herja (Baia Mare) ore deposit. The wall of the concretions is made up of siderite and includes jamesonite microcrystals. The concretions are 20 - 30 mm in diameter, the sideritic wal...

The pollution effect increased in the last decades due to industrial progress and also due to the orientation of economy towards consumption society. Raised pollution determines the scientists to find the ways to diminish the negative pollution effect. The technical revolution permitted the development of high performance instruments for pollutant...

1 ABSTRACT: The aim of this paper is to present some of the specific geochemical processes that take place in Roşia Montană mining region. The oxidation of sulphide minerals led to the removal of soluble metal ions from the waste dumps and other mining related wastes under the effect of rainfall. A specific biogeochemical activity in the mining are...

In the present study we try to use a new index called "pollution index" for define the pollution level of river using the dissolved heavy metal concentrations. This index derives from Müller’s geoaccumulation index but use the dissolved metal concentrations. The river water samples collected between the municipalities of Cheia and Muncel along a 54...

In the present study we try to use factor analysis in the characterisation of river water chemistry between the municipalities of Cheia and Muncel along a 54-km stretch of the Aries River (NW Romania). The results show that 4 factors can explain 88% of the water chemistry. The first factor explains 39% of the total data variance, and represents the...

 This paper examines two issues, the extensive pollution occurring in the Aries River, NW Romania, as a result of unchecked discharge of mining effluents into the river system, and the suitability of capillary electrophoresis (CE) as an analytical method for investigations into water chemistry. The results confirm the first objective by providing d...

The present article introduces the Cave Minerals of Romania database (CAMIRO 1.0), a computer-based program that allows cataloging of all known cave minerals species, including their main characteristics.

The paper presents two hydrothermal veins from Peştera din Valea Rea, found at the depth of -115 m on the cave's active passage. They have a column shape and oval section, with diameters between 30 and 50 cm and resulted by the filling of channels formed in hydrothermal karst conditions. Our studies (binoculary microscopy, transmission and reflexio...

On the basis of a fossiliferous assemblage, we confirm the Cenomanian age of the Cretaceous deposits from Cherghes. The most significant species are Ostrea (Alectryonia) carinata LAMARCK, Neithea (Neithea) zitteli (PIRONA) and Orbitolina (Orbitolina) concava (LAMARCK). The uper part of the succession, which includes an ammonite fauna, belongs very...

On the basis of a fossiliferous assemblage, we confirm the Cenomanian age of the Cretaceous depostts from Cherghe~. The most significant species are Ostrea (Alectryonia) carinata LAMARCK, Neithea (Neithea) zitteli (PIRONA) and Orbitolina (Orbitolina) concava (LAMARCK). The upper part of the succession, which includes an ammontte fauna, belongs very...

In the present study we try to use factor analysis in the characterisation of river water chemistry between the municipalities of Cheia and Muncel along a 54-km stretch of the Aries River (NW Romania). The results show that 4 factors can explain 88% of the water chemistry. The first factor explains 39% of the total data variance, and represents the...

In the present study we try to use a new index called "pollution index" for define the pollution level of river using the dissolved heavy metal concentrations. This index derives from Müller's geoaccumulation index but use the dissolved metal concentrations. The river water samples collected between the municipalities of Cheia and Muncel along a 54...