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@article{1579417,
author = {Štubňa, Ján and Bačík, Peter and Fridrichová, Jana and Hanus, Radek and Illášová, Ľudmila and Milovská, Stanislava and Škoda, Radek and Vaculovič, Tomáš and Čerňanský, Slavomír},
article_location = {Basel},
article_number = {3},
doi = {http://dx.doi.org/10.3390/min9030164},
keywords = {andradite; demantoid; gemstone; Raman spectroscopy; UV-Vis-NIR spectroscopy; X-ray fluorescence spectroscopy; gem-quality; garnet},
language = {eng},
issn = {2075-163X},
journal = {Minerals},
title = {Gem-Quality Green Cr-Bearing Andradite (var. Demantoid) from Dobsina, Slovakia},
url = {https://www.mdpi.com/2075-163X/9/3/164/htm},
volume = {9},
year = {2019}
}
TY - JOUR
ID - 1579417
AU - Štubňa, Ján - Bačík, Peter - Fridrichová, Jana - Hanus, Radek - Illášová, Ľudmila - Milovská, Stanislava - Škoda, Radek - Vaculovič, Tomáš - Čerňanský, Slavomír
PY - 2019
TI - Gem-Quality Green Cr-Bearing Andradite (var. Demantoid) from Dobsina, Slovakia
JF - Minerals
VL - 9
IS - 3
SP - 1-12
EP - 1-12
PB - MDPI
SN - 2075163X
KW - andradite
KW - demantoid
KW - gemstone
KW - Raman spectroscopy
KW - UV-Vis-NIR spectroscopy
KW - X-ray fluorescence spectroscopy
KW - gem-quality
KW - garnet
UR - https://www.mdpi.com/2075-163X/9/3/164/htm
L2 - https://www.mdpi.com/2075-163X/9/3/164/htm
N2 - 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.
ER -
ŠTUBŇA, Ján, Peter BAČÍK, Jana FRIDRICHOVÁ, Radek HANUS, Ľudmila ILLÁŠOVÁ, Stanislava MILOVSKÁ, Radek ŠKODA, Tomáš VACULOVIČ a Slavomír ČERŇANSKÝ. Gem-Quality Green Cr-Bearing Andradite (var. Demantoid) from Dobsina, Slovakia. \textit{Minerals}. Basel: MDPI, 2019, roč.~9, č.~3, s.~1-12. ISSN~2075-163X. Dostupné z: https://dx.doi.org/10.3390/min9030164.
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