Cristina Ghinet - Academia.edu (original) (raw)

Papers by Cristina Ghinet

Phosphogypsum is a technogenic product remaining after the extraction of phosphoric acid from raw... more Phosphogypsum is a technogenic product remaining after the extraction of phosphoric acid from raw phosphate, mainly apatite. The phosphate rock mainly composed of apatite, and originating from Morocco, Russia, Syria, Jordan and India, is treated with concentrated sulfuric acid (96%), after fine crushing to supra colloidal size and passing into an aqueous solution of phosphoric acid. The morphology of crystals is influenced by the conditions of phosphoric acid manufacture. Most of the analyzed crystalline phases, especially gypsum, have micronic size, are very water absorbing and are detectable only at the level of crystalline individual through the scanning electron microscopy.

Minerals

A carbonate-bearing, fluorine-overcompensated fluorapatite (F = 4.42 wt.% as compared with 3.77 w... more 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 chemical structural formula (with carbonate not included) is: (Ca4.989Mn0.001Fe2+0.003Mg0.003Ce0.001La0.001)(P2.992Si0.008)(O11.894F1.202Cl0.001). No major structural distortions due to (CO3F)3--for-(PO4)3- replacement were identified by single crystal X-ray diffraction, Raman or FTIR. The mineral crystallizes in space group P63/m, having as cell parameters a = 9.3818(1) Å and c = 6.8872(1) Å. The indices of refraction are: ω = 1.634(2) and ε = 1.631(1). The calculated density is Dx = 3.199 g/cm3 and the measured density is Dm = 3.201(3) g/cm3. Calculation of the Gladstone–Dale compatibility indices gave in all cases values indicative of super...

The Canadian Mineralogist, 2015

A shallow-level dioritic pluton of Upper Cretaceous age caused extensive contact metamorphism of ... more 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, akermanite-rich melilite, Ti-rich calcic garnet, and pyrrhotite. A second, subsequent paragenesis (stage II) is due to local decreases in fluid pressure and includes gehlenite, Ti-poor calcic garnet, monticellite, Al-rich diopside, magnetite, perovskite, and probably a Ca-Si mineral (kilchoanite?). An early hydrothermal stage (stage III) produced retrogression of the first two stages and a paragenesis including vesuvianite, clintonite, fukalite, katoite, and hydroxylellestadite. A second, late hydrothermal event (stage IV) resulted in the formation of clinochlore, talc, epidote, zeolites (scolecite and thomsonite-Ca), thaumasite, and tobermorite. A last, weathering, paragenesis corresponding to stage V includes allophane (C-S-H gels) and probably portlandite, unpreserved because of its transformation to aragonite, then calcite. The peak metamorphic conditions during the prograde evolution are estimated to have been 750–800 °C for a fluid pressure of up to 0.5 kbar. The main constants determined from chemical, optical, and X-ray powder analyses of these mineral species are reported here. This work documents the first occurrence of katoite and the second occurrences of perovskite, fukalite, and hydroxylellestadite in the Romanian skarns.

Minerals

An ammonium-bearing fluorapophyllite-(K) occurs as a late hydrothermal product in the outer endos... more An ammonium-bearing fluorapophyllite-(K) occurs as a late hydrothermal product in the outer endoskarn zone from Aleului Valley (N 46°37′04″, E 22°35′22″), located at the contact of the granodiorite laccolith from Pietroasa, of Upper Cretaceous age, with Anisian dolostones. Associated minerals are wollastonite, K feldspar, diopside, fluorapatite, talc, and pectolite. The chemical structural formula is [K0.985Na0.012(NH4)0.076]Σ=1.073(Ca4.009Mn0.001Fe2+0.003Mg0.002Ba0.001)Σ=4.016(Si7.953Al0.047) O20.029[F0.899(OH)0.101]·8.059H2O. The structure was successfully refined as tetragonal, space group P4/mnc, with cell parameters of a = 8.9685(1) Å and c = 15.7885(5) Å. The indices of refraction are ω = 1.534(1) and ε = 1.536(1). The calculated density is Dx = 2.381 g/cm3, in good agreement with the measured density, Dm = 2.379(4) g/cm3. The thermal analysis shows that the mineral completely dehydrates at up to 450 °C (endothermic effects at 330, 371, and 448 °C) and loses ammonium at 634 °C...

Goldschmidt2021 abstracts

Insignificant in terms of mineralization, the skarns of Oravita are scientifically interested bec... more Insignificant in terms of mineralization, the skarns of Oravita are scientifically interested because of their mineralogical associations. The higher crystallinity and good natural conditions (they are generally barren) are two characteristics of this rocks that can provide the ideally system to understand the behavior of the mineralogical components in certain conditions of temperature and pressure, but also for the hydrated carbonate phases whose forming understanding may be useful in the applied mineralogy. The occurrence of skarns from Oravia includes, as representative species, gehlenite, calcic garnet, monticellite, ellestadite-(OH), vesuvianite, that means in the geochemically terms CaO – SiO 2 – H 2 O – Al2O 3 system, usually described as C-S-H-A phases by the cement researches, difficult to study because of the small dimensions of the compounds crystals. The inner skarn zone is dominated by the presence of the gehlenite, an aluminum calcium silicate whose formation involves...

Phosphogypsum is a secondary technogenic product of the acid phosphate fertilizer industry, deriv... more Phosphogypsum is a secondary technogenic product of the acid phosphate fertilizer industry, derived from phosphate rock during the production of phosphoric acid. Phosphate rock mainly composed of apatite, originating from Morocco, Russia, Syria, Jordan and India, is treated with concentrated sulfuric acid (96%), after fine crushing to supra colloidal size and passing into an aqueous solution of phosphoric acid. The solution is recirculated to produce gypsum, phosphoric and hydrofluoric acid. Scanning electron microscopy was performed on samples taken from the deposits of Turnu Măgurele, Valea Călugarească, Năvodari and Bacău. The analysis resulted in the definition of four morphological types of phosphogypsum. All of the analyzed samples of the first morphological type have compositions close to stoichiometry. The gypsum crystals are prismatic to acicular, showing perfect cleavage after [001]. Individual crystals have lengths ranging from 10 to 120 μm (Fig. 1). The phosphogypsum crystals of the second morphological group are grouped in polycrystalline, weakly cohesive aggregates. A morphological feature of this type consists of the homogeneous crystal size. Crystal morphology of this group is relatively large and tends to form aggregates of accretion, with randomly oriented and interlocking crystals. The crystal size varies from 100 μm to 1 mm (Fig. 2). The third morphological group of phosphogypsum is dominated by the presence of crystalline aggregates that are similar to the “sand roses”. The largest dimension of the aggregates reaches 1 mm (Fig. 3). The fourth morphological group of phosphogypsum is common at the lower levels of all stockpiles and consists of a series of crystalline, cauliflower-like aggregates. These are practically similar to those of the third group, but the crystalline forms of gypsum are difficult to distinguish (Fig. 4).

A shallow-level dioritic pluton of Upper Cretaceous age caused extensive contact metamorphism of ... more A shallow-level dioritic pluton of Upper Cretaceous age caused extensive contact metamorphism of a Callovian - Aptian calcareous sequence at Oraviţa - Ciclova (Banat, Romania), at about 35 km SSW of Reşita, the major city in the area. The resulted high-temperature skarn can be better observed on Crişenilor Brook, where it crops out at about 200 m upstream from its confluence with the Oraviţa Valley. The skarn from Crişenilor Brook is clearly zoned, the zones being individualized by the massive presence of one distinct mineral species. This zoning is, from the outer to the inner part of the metasomatic area: calcite (marble) / vesuvianite (+ wollastonite 2M) / gehlenite / plagioclase + diopside + calcic garnet / diorite. The inner endoskarn is largely dominated by the abundant development of calcic garnet (Grs 33.78 – 82.07 mol.%, Adr 13.45 – 64.36 mol.% with up to 9.47 mol.% morimotoite in the solid solution), titanite and diopside, in a mass conserving albite-substituted plagioclas...

Mineralogical Magazine, 2013

The Canadian Mineralogist, 2011

Gehlenite is a common mineral in three high-temperature calcic skarns in Romania: Măgureaua Vaţei... more Gehlenite is a common mineral in three high-temperature calcic skarns in Romania: Măgureaua Vaţei and Cornet Hill in Apuseni Mountains and Oraviţa in Banat. In all three occurrences, a gehlenite zone occurs within the contact between dioritic or monzodioritic bodies of Upper Cretaceous age and carbonaceous sequences of Mesozoic age. The melilite solid-solutions vary from Ak 34.1 to Ak 51.2 (mean Ak 41.2) at Oraviţa, from Ak 30.4 to Ak 42.9 (mean Ak 38.3) at Măgureaua Vaţei, and from Ak 24.3 to Ak 41.7 (mean Ak 32.9) at Cornet Hill, respectively. The content of "Na-melilite" is low, from up to 1.96 mol.% at Cornet Hill to up to 3.60 mol.% at Oraviţa. The cell parameter a ranges from 7.679(3) to 7.734(3) Å at Oraviţa, from 7.683(4) to 7.735(1) Å at Măgureaua Vaţei, and from 7.684(3) to 7.733(1) Å at Cornet Hill, whereas c varies from 5.043(3) to 5.065(3) Å at Oraviţa, from 5.040(1) to 5.070(3) Å at Măgureaua Vaţei, and from 5.044(1) to 5.067(4) Å at Cornet Hill. It is not possible to quantify the variations in the crystallographic parameters by considering only the åkermanitic substitution because the "Na-melilite" and "Fe-åkermanite" substitutions also play an important role. The cell parameter a remains practically constant within experimental errors, in spite of the increasing åkermanite-for-gehlenite substitution, due to the opposite influence of the "Na-melilite" component. The åkermanite substitution prevails over the opposite influence of "Na-melilite" in increasing the cell volume, and is additive to the influence of "Na-melilite" in decreasing the cell parameter c. The record in the infrared-absorption spectra of bands located at ~855 cm-1 and ~670 cm-1 , respectively, which may be tentatively assigned to Al-O-Al stretching, is indicative of the presence of gehlenite-rich members of the melilite group in all the three occurrences.

Mineralogical Magazine, 2013

Phosphogypsum is a technogenic product remaining after the extraction of phosphoric acid from raw... more Phosphogypsum is a technogenic product remaining after the extraction of phosphoric acid from raw phosphate, mainly apatite. The original phosphate rock contains large amounts of REE, mainly replacing Ca from apatite or included in other phosphate structures. About 70% of the REE contents are stacked in the phosphogypsum obtained after sulfuric attack of the raw phosphate and much less in the case of hydrochloric attack. In Romania, the sulfuric attack through the hemidihydrate (HDH) or dihydrate (DH) procedures was extensively used to obtain phosphoric acid at Turnu Măgurele (TM), Valea Călugărească (VC), Năvodari (N) and Bacău (B). Inductively coupled plasma - atomic emission spectrometry (ICP-AES) analyses performed on selected samples of phosphogypsum from the four deposits showed that the contents in the main REE (cerium, erbium, neodymium, thorium, ytterbium) are specific for the phosphogypsum issued from the processing of sedimentary raw phosphates.

Goldschmidt2021 abstracts

Minerals

The Canadian Mineralogist, 2015

Minerals

Goldschmidt2021 abstracts

A shallow-level dioritic pluton of Upper Cretaceous age caused extensive contact metamorphism of ... more A shallow-level dioritic pluton of Upper Cretaceous age caused extensive contact metamorphism of a Callovian - Aptian calcareous sequence at Oraviţa - Ciclova (Banat, Romania), at about 35 km SSW of Reşita, the major city in the area. The resulted high-temperature skarn can be better observed on Crişenilor Brook, where it crops out at about 200 m upstream from its confluence with the Oraviţa Valley. The skarn from Crişenilor Brook is clearly zoned, the zones being individualized by the massive presence of one distinct mineral species. This zoning is, from the outer to the inner part of the metasomatic area: calcite (marble) / vesuvianite (+ wollastonite 2M) / gehlenite / plagioclase + diopside + calcic garnet / diorite. The inner endoskarn is largely dominated by the abundant development of calcic garnet (Grs 33.78 – 82.07 mol.%, Adr 13.45 – 64.36 mol.% with up to 9.47 mol.% morimotoite in the solid solution), titanite and diopside, in a mass conserving albite-substituted plagioclas...

Mineralogical Magazine, 2013

The Canadian Mineralogist, 2011

Mineralogical Magazine, 2013

Phosphogypsum is a technogenic product remaining after the extraction of phosphoric acid from raw... more Phosphogypsum is a technogenic product remaining after the extraction of phosphoric acid from raw phosphate, mainly apatite. The original phosphate rock contains large amounts of REE, mainly replacing Ca from apatite or included in other phosphate structures. About 70% of the REE contents are stacked in the phosphogypsum obtained after sulfuric attack of the raw phosphate and much less in the case of hydrochloric attack. In Romania, the sulfuric attack through the hemidihydrate (HDH) or dihydrate (DH) procedures was extensively used to obtain phosphoric acid at Turnu Măgurele (TM), Valea Călugărească (VC), Năvodari (N) and Bacău (B). Inductively coupled plasma - atomic emission spectrometry (ICP-AES) analyses performed on selected samples of phosphogypsum from the four deposits showed that the contents in the main REE (cerium, erbium, neodymium, thorium, ytterbium) are specific for the phosphogypsum issued from the processing of sedimentary raw phosphates.

Goldschmidt2021 abstracts