2019
Gem-Quality Green Cr-Bearing Andradite (var. Demantoid) from Dobsina, Slovakia
ŠTUBŇA, Ján, Peter BAČÍK, Jana FRIDRICHOVÁ, Radek HANUS, Ľudmila ILLÁŠOVÁ et. al.Základní údaje
Originální název
Gem-Quality Green Cr-Bearing Andradite (var. Demantoid) from Dobsina, Slovakia
Autoři
ŠTUBŇA, Ján (703 Slovensko, garant), Peter BAČÍK, Jana FRIDRICHOVÁ, Radek HANUS, Ľudmila ILLÁŠOVÁ, Stanislava MILOVSKÁ, Radek ŠKODA (203 Česká republika, domácí), Tomáš VACULOVIČ (203 Česká republika, domácí) a Slavomír ČERŇANSKÝ
Vydání
Minerals, Basel, MDPI, 2019, 2075-163X
Další údaje
Jazyk
angličtina
Typ výsledku
Článek v odborném periodiku
Obor
10504 Mineralogy
Stát vydavatele
Švýcarsko
Utajení
není předmětem státního či obchodního tajemství
Odkazy
Impakt faktor
Impact factor: 2.380
Kód RIV
RIV/00216224:14310/19:00111294
Organizační jednotka
Přírodovědecká fakulta
UT WoS
000464443000002
Klíčová slova anglicky
andradite; demantoid; gemstone; Raman spectroscopy; UV-Vis-NIR spectroscopy; X-ray fluorescence spectroscopy; gem-quality; garnet
Štítky
Příznaky
Mezinárodní význam, Recenzováno
Změněno: 26. 3. 2020 13:40, Mgr. Marie Šípková, DiS.
Anotace
V originále
Andradite, variety demantoid, is a rare gem mineral. We describe gem-quality garnet crystals from serpentinized harzburgites from Dobsina, 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 to 3.84 g center dot cm(-3). Andradite var. demantoid appeared red under Chelsea filter observation. Both samples contained fibrous crystalline inclusions with the typical "horsetail" arrangement. The studied garnet had a strong Fe3+ dominant andradite composition with 1.72-1.85 apfu Fe3+, Cr3+ up to 0.15 apfu, Al3+ 0.03 to 0.04 apfu, V3+ up to 0.006 apfu substituted for Fe3+, Mn2+ up to 0.002 apfu, and Mg up to 0.04 apfu substituted for Ca. Raman spectrum of garnet showed three spectral regions containing relatively strong bands: I-352-371 cm(-1), II-816-874 cm(-1), and III-493-516 cm(-1). The optical absorption spectrum as characterized by an intense band at 438 nm and two broad bands at 587 and 623 nm and last one at 861 nm, which were assigned to Fe3+ and Cr3+. Transmission was observed in the ultraviolet spectral region (<390 nm), near the infrared region (700-800 nm), and around 530 nm in the green region of visible light, resulting in the garnet's green color.