Jana Fridrichová

Comenius University Bratislava · Department of Mineralogy Petrology

Various chrysoberyl varieties (non‐phenomenal chrysoberyl, alexandrite and cymophane) are gemstones of high demand; therefore, they are subjected to numerous substitutions by other materials and synthetic analogues. To address this issue, non‐destructive methods for studying gemstones are highly sought after. Raman spectroscopy is one of the most s...

A complex crystal-chemical investigation based on spectroscopic methods, Electron MicroProbe Analysis (EMPA), and Laser Ablation Inductively Coupled Plasma Mass Spectrometry (LA-ICP-MS) was made on sphalerite samples from the Terézia and Rozália veins in the Banská Štiavnica ore district. The yellow (sample A) and olive-green sphalerite (C) are in...

The beryllium silicate minerals phenakite and bertrandite have been identified in granitic pegmatite dykes of beryl-columbite subtype of Variscan age (~340-355 Ma), associated with S- to I-type granitic rocks of the Tatric Superunit, Western Carpathians (Slovakia). These two beryllium silicates and associated minerals were characterized by elect...

The study reveals the relationships between crystal-chemical and genetic properties of beryl from several rare-element granitic pegmatites of the LCT family from the Damara Belt, Namibia. Based on their chemical compositions, the studied beryl samples can be divided into two groups. Beryl from the first group (the Engelbrecht's and Etusis pegmatite...

We studied 12 crystal fragments of natural spinel from Mogok, Myanmar and Lục Yên, Vietnam. All samples were crystal fragments of various shapes and sizes and several of them had gemological quality. Studied samples are enriched in Cr, V, Fe2+, Fe3+, Zn, which are responsible for its resulting color. They could be divided into groups of V-Cr spinel...

Theoretical bond-length calculations from ideal bond valences for each ion and coordination allows for the prediction of ion site preference and partitioning in tourmaline structures at low-pressure conditions. A comparison of calculated data with published bond-length values enables the determination of the range of structurally stable bond length...

In talc-magnesite veins in serpentinite near Muránska Dlhá Lúka (MDL), Slovakia, yellow euhedral to subhedral crystals apatite of a gem quality occur. It has a composition of hydroxylapatite with F − varying between 0.29 and 0.34 apfu, Cl − in range of 0.02-0.05 apfu and calculated OH − content between 0.62-0.68 apfu. Moreover, [CO 3 ] 2− molecules...

Different structure and symmetry of spinel and chrysoberyl influence their luminescence spectra Observed with Raman spectroscopy. Luminescence bands of spinel at 677, 685, 697, 710 a 718 nm were assigned to Cr3+. Luminescence duplet located at 685 and 687 nm belongs to R1 and R2–lines for the Cr3+ ion, the electron transition 2Eg → 4A2g, N1 and N4...

The site preference for each cation and site in beryl based on bond-length calculations was determined and compared with analytical data. Tetrahedral SiO4 six-membered rings normally have no substitutions which results from very compact Si4+–O bonds in tetrahedra. Any substitution except Be would require significant tetrahedral ring distortion. The...

Illitic clay from the locality of Liepa, Latvia, was investigated using dynamic thermomechanical analysis during the heating and cooling stages of firing. Differential thermal analysis, thermogravimetry, thermodilatometry, X-ray diffraction and porosimetry were also performed to shed light on the processes influencing the elastic properties of clay...

We studied three samples from the following localities: Madagascar (RMA-1) and Mysore, India (RMI-1 and RMI-2). The RMA-1 and RMI-1 samples have the most intensive band at the 690 and 698 nm. The RMI-2 sample has a broader luminescence band with two intense bands at 690 and 699 nm. In the region of about 692 nm (2 T1g→ 4 A2g), and 694 nm (2 Eg→ 4 A...

Journal of Gemmology Vol. 36 No. 5 pp. 409-410

Andradite, variety demantoid, is a rare gem mineral. We describe gem-quality garnet crystals from serpentinized harzburgites from Dobšiná, Slovakia which were faceted. Both the andradite samples were transparent, with a vitreous luster and a vivid green color. They were isotropic with refractive indices >1.81. The measured density ranged from 3.82...

Crystal-chemical properties, and octahedral substitution role in particular, of beryl from weakly fractionated intragranitic pegmatite at Predné Solisko, Vysoké Tatry Mts. (Slovakia) is described in detail. The studied beryl was found in granitic pegmatite derived from biotite I-type granodiorite. It has a weakly zoned core with variable Fe and Mg...

Fourteen gem-quality green-coloured beryl samples of different origin were investigated by standard gemmological methods and Raman, X-ray fluorescence and optical absorption spectroscopy. All investigated 14 samples were identified as beryl by Raman spectroscopy. Five main transition elements were detected (Cr, V, Fe, Cu, Ni). Six samples were sign...

RESUMO: O recentemente definido supergrupo da gadolinita, aprovado pela Comissão de Novos Minerais, Nomenclatura e Classificação da Associação Mineralógica Internacional (proposta IMA-CNMNC 16-A), inclui espécies minerais que têm fórmula química geral A2MQ2T2O82 e pertencem às classes dos silicatos, fosfatos e arsenatos. Os sítios estruturais são...

Granitic pegmatites are relatively common rocks in pre-Alpine (Paleozoic) crystalline basement of the Tatric and Veporic Units of the Western Carpathians. They are genetically connected with orogen-related Variscan granitic rocks of S-or I-type affinity. The most evolved West-Carpathian pegmatites contain beryl and/or Nb-Ta oxide minerals (columbit...

Spinel (MgAl2O4) contains various concentrations of Cr3+ ions in the octahedral coordination. Spinel belongs to the cubic space group Oh7 with eight formula units per cell and two sites for metal ions. The A site (Mg) has the tetrahedral coordination with Td symmetry and the B site (Al, Cr) is six-fold distorted with octahedral coordination in D3d...

Four beryl samples from various Namibian localities Etusis (ETU), Kudoberg (KUD), Baobismond (BAO) – Karibib and Engle Brecht (EN) – Strathmore) were investigated by wide spectrum of analytical methods. The studied beryls are derived from complex-type petalite-subtype pegmatites of LCT family. BAO and KUD samples are assigned to normal beryls (0.99...

Laser has dual role in mineralogy; minerals are used as a source of laser radiation and laser is employed in mineral analytical study. Therefore, we used spectroscopic methods to study Cr-bearing minerals, which are potential laser sources. Chemical composition was determined by XRF analysis, and shows that ruby is enriched in Fe, Ti and Cr, alexan...

The newly defined gadolinite supergroup approved by the IMA CNMNC (vote 16-A) includes mineral species that have the general chemical formula A2MQ2T2O8’2 and belong to silicates, phosphates and arsenates. Each site is occupied by: A Ca, REE (Y and lanthanoids), actinoids, Pb, Mn2þ, Bi; M Fe, □ (vacancy), Mg, Mn, Zn, Cu, Al; Q B, Be, Li; T Si, P, As...

Tourmaline-supergroup minerals are common gangue minerals in Sb-hydrothermal veins on Betliar – Straková, Čučma – Gabriela and Rožňava – Peter-Pavol vein deposits in the Rožňava area, Slovakia. Tourmaline-supergroup minerals form relatively large prismatic to radial aggregates of parallel black to greyish-black crystals. Tourmaline-supergroup miner...

Red beryl from Utah is chemically homogeneous and contains only Fe < 0.163, Mn < 0.018, and Mg < 0.016 apfu. Channel sites contain only up to Cs 0.011, K 0.009, Rb 0.004, and Na 0.004 apfu. This suggests only very slight tetrahedral (Cs,K,Rb)Li□-1Be-1 substitution, octahedral Na(Fe²⁺,Mg)□-1Al-1 substitution can be excluded. Fe and Mn are trivalent...

Gadolinite supergroup was newly defined and approved by the CNMNC IMA. It consists of mineral species having the monoclinic P2 1 /c crystal structure with the general chemical formula A 2 MQ 2 T 2 O 8 ϕ 2. Each site is occupied as follows: A-Ca, REE (Y and lanthanoids), actinoids, Pb, Mn 2+ , Bi; M-Fe, □ (vacancy), Mg, Mn, Zn, Cu, Al; Q-B, Be, Li;...

Abstrakt Novo definovaná gadolinitová superskupina bola schválená Komisiou pre nové minerály, nomenklatúru a klasifikáciu pri Medzinárodnej mineralogickej asociácii (CNMNC IMA-Commission on New Minerals, Nomenclature and Classification of the International Mineralogical Association) (Bačík et al., 2017). Táto superskupina obsahuje minerály, ktoré m...

Nine beryl samples from Western Carpathians, Slovakia, were investigated by infrared and Raman spectroscopy and differential thermal analysis. Two types of water H2O I and H2O II were detected. Infrared spectroscopy proved the presence of water type I and II in the presence of alkali cations with several bands: (1) symmetric stretching vibration—ν1...

Faceted tourmaline gemstones obtained from commercial sources as elbaites were studied with non-destructive spectroscopic methods. We applied Raman spectroscopy for mineral identification and UV/Vis/NIR spectroscopy for determination of chromophores. We identified the most of samples as fluor-elbaite to elbaite by Raman spectroscopy except one samp...

Eleven brilliant cut yellow and brown diamonds were studied by non-invasive spectroscopic methods and devices. At first, identification was proven by Raman spectroscopy according to presence of Diamond Raman band at ca. 1330 cm–1 in each sample. UV/Vis/NIR spectroscopy was used as a potential tool to determine the diamond type. All studied stones w...

This contribution reviews and affords new insights into the crystal chemistry of gadolinite-datolite group (GDG) silicates by re-examination of published and unpublished analytical data. More than 200 electron microprobe analyses (EMPA) and data from both single-crystal and powder X-ray diffraction of 53 samples of GDG silicates were collected to s...

Optical and crystal-chemical changes in two beryl varieties after the heat treatment were determined using a wide spectrum of analytical methods. Studied aquamarines are generally more enriched in Fe (up to 0.25 apfu) and alkali (up to 0.08 apfu) than yellow beryls (up to 0.07 apfu Fe, up to 0.04 apfu alkali). The determined c/a ratio of 0.997-0.99...