Delia-Georgeta Dumitras

Geological Institute of Romania | IGR · Mineralogy

In the Mănăila alpine area, the soil layer developed in situ on top of the sericite-schists, which belong to the Tulghes 3 metamorphic unit. The aim of the present work was to determine the degree of soil formation using both mineralogical and geochemical exploration methods. XRD, FTIR and SEM-EDS results showed that the soil constituents were dioc...

A carbonate-bearing, fluorine-overcompensated fluorapatite (F = 4.42 wt.% as compared with 3.77 wt.% F in the Ca5(PO4)3F end-member), was identified in forsterite-bearing skarns from Valea Rea (N 46°39′48″, E 22°36′43″), located near the contact of the granodiorite laccolith from Budureasa, of Upper Cretaceous Age, with Anisian dolostones. The chem...

The rare minerals, inesite, Ca2Mn 2+ 7Si10O28(OH)2·5H2O, hubeite, Ca2Mn 2+ Fe 3+ Si4O12(OH)·2H2O, and ruizite, Ca2Mn 3+ Si4O11(OH)4·2H2O, were determined, for the first time, by optical and XRD analyses, at Cavnic (Baia Mare Neogene metallogenetic district, Eastern Carpathians, Romania) in a gold-bearing, base metal deposit. Inesite was refined as...

From a scientific point of view, most paleontological sites in Dobrogea are well documented in terms of scientific value (fossil content and geological framework, educational, aesthetic and even commercial value, as described in previous works) and in terms of area (established by law: surface, location). This paper brings an update of some sites i...

A rich association of primary guano minerals, including taranakite, hydroxylapatite, brushite and gypsum with relicts of illite, kaolinite, alpha (low) quartz and calcite, was identified in the fossil bat guano deposit from Gura Dobrogei Cave, Dobrogea County, Romania. Gypsum and Ca phosphates developed preferentially on the carbonate bedrock or on...

A rich association of primary guano minerals, including taranakite, hydroxylapatite, brushite and gypsum with relicts of illite, kaolinite, alpha (low) quartz and calcite, was identified in the fossil bat guano deposit from Gura Dobrogei Cave, Dobrogea County, Romania. Gypsum and Ca phosphates developed preferentially on the carbonate bedrock or on...

This paper intends to analyse the characteristics of granulated and non-granulated blast furnace slag used in preparing the road concrete, respectively their influence on the most important characteristics of the concrete, such as consistency, apparent specific gravity, occluded air volume, mechanical resistance, wear resistance and freeze-thaw res...

This paper intends to analyse the characteristics of granulated and non-granulated blast furnace slag used in preparing the road concrete, respectively their influence on the most important characteristics of the concrete, such as consistency, apparent specific gravity, occluded air volume, mechanical resistance, wear resistance and freeze-thaw res...

A shallow-level monzodioritic to quartz-monzodioritic pluton of the Upper Cretaceous age caused contact metamorphism of Tithonic-Kimmeridgian reef limestones at Măgureaua Vaţei (Metaliferi Massif, Apuseni Mountains, Romania). The preserved peak metamorphic assemblage includes gehlenite (Ak 33.64-38.13), monticellite, wollastonite-2M, Ti-poor calcic...

The natural form under which iron disulphide is ordered is isometric (pyrite) or orthorhombic (marcasite). The most common case is where the form of crystallization is represented by pyrite (cubes or radial and framboidal arrangements). The degree of alteration of the samples is variable, mainly related to the actual amount of pyrite, as well as re...

Abstract “Canaralele din Portul Hârșova” geosite is integrated into ‘Canaralele Dunarii’ Natura 2000 site (ROSCI0022), and represents the northern part of the geologic profile in Jurassic deposits that is exposed along the Danube River valley between Hârșova and Capidava. This sector exibits Middle and Upper Jurassic deposits, developed in bioherma...

The Albeşti granite, of Early Ordovician age, was formed by crustal anatexis, experienced a medium temperature and medium-to-high pressure metamorphic event and is now hosted by the crystalline formations of the Leaota Mountains (South Carpathians), where it forms stratigraphically concordant lenses. Its most striking feature, similar to other Euro...

The Early Ordovician Albești Granite was formed by crustal anatexis, experienced a medium temperature and medium to high pressure metamorphic event and is now hosted by the crystalline formations of the Leaota Mts. (South Carpathians) where it forms stratigraphically concordant lenses. Its most striking feature, similar to other European granites o...

This paper presents the characterization of a Ni-Cu thin layer electrodeposited onto a steel substrate. The characterization of these films was performed with X-ray diffraction spectroscopy, Raman spectroscopy and Scanning electron microscopy. The results of the XRD analysis showed a Face Centered Cubic structure and the Raman spectroscopy indicate...

Szaibelyite samples from five boron-bearing magnesian skarns in Romania (Ocna de Fier, Maşca-Băişoara, Cacova Ierii, Băiţa Bihor and Pietroasa) were analysed in order to improve on optical, chemical, thermal, infrared and X-ray database. In all the five occurrences, the mineral is present in the outer skarn zones developed at the contact of igneous...

Phosphogypsum is a technogenic product resulted after the extraction of phosphoric acid from raw phosphate (apatitic) rock by nitric or sulfuric leaching. In Romania, huge stacks of phosphogypsum resulted from sulfuric leaching are located at Valea Călugărească (56 ha), Turnu Măgurele (64 ha), Năvodari (48 ha) and Bacău (20 ha). The chemistry of di...

The National Museum of Geology of Romania is hosted by the historical building of the Geological Institute of Romania, declared a monument of architecture and erected in 1906 - 1909. The museum encapsulates all the branches of the geological sciences (which are shown as if illustrating a treatise of geology) and posesses 85000 exhibits. The 22 hall...

The National Museum of Geology of Romania is hosted by the historical building of the Geological Institute of Romania, declared a monument of architecture and erected in 1906 - 1909. The museum encapsulates all the branches of the geological sciences (which are shown as if illustrating a treatise of geology) and posesses 85000 exhibits. The 22 hall...

Material from the type locality, the “dry” Cioclovina Cave, Şureanu Mountains, Romania, was re-examined in order to update the descriptive mineralogy of ardealite, a rare hydrated calcium acid phosphate sulfate. Ardealite from Cioclovina has a S/P ratio ranging between 1/0.87 and 1/0.98. Although S remains the main tetrahedral cation in the structu...

The present study highlights the fact that having the mark of the rocks through which they pass, geothermal waters from Beius Basin have, in their natural state, an important content of metals. This fact encourages us to believe that, through anthropic methods, it is possible to increase even more this content of metals in the exploited geothermal...

Diatomite samples taken from the Urluia – Adamclisi localities, South Dobrogea region (Romania) have been studied by X-ray fluorescence, wet-chemical analysis, scanning electron microscopy (SEM), FTIR and X-ray powder diffraction. The mineralogy of all but one deposit is predominated by the presence of quartz, amorphous silica, feldspars and clay m...

Detailed information concerning the pre-and post-burial modifications that affect the remains of ancient organisms (i.e. their taphonomy) are instrumental in appreciating the ways the fossil record is biased by biological and geological processes. Reconstructing taphonomic history also allows a more accurate understanding of the paleoenvironmental...

A shallow-level dioritic pluton of Upper Cretaceous age caused extensive contact metamorphism of a Mesozoic calcareous sequence at Oraviţa-Ciclova in Romania. The peak metamorphic assemblage (stage I) includes wollastonite, åkermanite-rich melilite, Ti-rich calcic garnet, and pyrrhotite. A second, subsequent paragenesis (stage II) is due to local d...

Ardealite from Cioclovina was first described by Schadler (1932) from the fossil bat-guano deposit in the "dry" Cioclovina Cave (Şureanu Mountains, Romania). The mineral occurs as white pearly or earthy masses of chalky appearance. Our investigation shows that the mineral can be characterized as a P-substituted sulfate. Wet-chemical and ICP-AES ana...

A shallow-level monzodioritic to quartz-monzodioritic pluton of Upper Cretaceous age caused extensive contact metamorphism of Tithonic - Kimmeridgian reef limestones at Măgureaua Vaţei (Metaliferi Massif, Apuseni Mountains, Romania). The preserved peak metamorphic assemblage includes gehlenite, monticellite, wollastonite-2M, Ti-poor calcic garnet,...

In the Banat area, the contact metamorphism is related to various shallow level magmatic intrusions of Upper Cretaceous age, that lead in the Ciclova – Oraviţa zone to the formation of some particular, high-temperature calc-skarns deposits. Gehlenite-bearing skarns occur at the very contact between dioritic or monzodioritic bodies and carbonaceous...

Wollastonite from three occurrences of high-temperature skarns in Romania: Măgureaua Vaţei (MV), Cornet Hill (CH) and Oraviţa (Or), was investigated from crystal-chemical and crystallographical point of view, in order to assay its use as industrial mineral. In all cases, wollastonite-2M occurs in gehlenite-bearing skarns within the contact between...

Diatomaceous earths from six occurrences in Romania were analyzed from chemical and mineralogical point of view in order to check the optimal deposit for providing absorbers and filtration media for essential oils. The characterization was done using X-ray fluorescence, wet-chemical analysis, FTIR and X-ray powder diffraction. The target occurrence...

The black sand of the Chituc marine sand bank, northern of the city of Navodari (Romania), presents anomalous high radioactivity. Field measurements recorded in some places dose rate up to 200 nSv/h, significantly overpassing the average value of 44 ± 20 nSv/h along the entire Southern sector of Romanian Black Sea shore. Gamma ray spectrometry per...