TY - JOUR N2 - Ch-chalcedony is a green colored member of the quartz group of gem stones. The appearance of Ch-chalcedony is very similar to that of chrysoprase. Differently, Ch-chalsedonies have a chromium element instead of a nickel element as a trace element. Green quartz used in jewelery as a seal stone, in necklaces and rings and has been one of the most valuable quartz varieties throughout history, with its beautiful green color,more rare than other quartz varieties. The Ch-chalcedonies in the North Anatolian region is yellowish-white, brownish gray, light green to dark green in color ranging from several centimeters to one meter thick in veins and lenses in the Lower-Middle Eocene dolomitic limestones. Ch-chalcedonies are composed of fine-grained and occasionally fibrous needle-like quartz; in some examples, quartz is present together with cristobalite, tridimite and cuspidine minerals. According to geochemical investigations in Ch-chalcedonies, the main oxides that were determined are as follows: SiO2 was observed in the range of 95.86–97.81%, Fe2O3 was observed in the range of 0.61–0.91% and Cr2O3 was observed in the range of 0.125–0.168%. A trace element analysis of Ch-chalcedonies, shows their significant enrichments in: Ni, Mo, Cu, Mn, V, Cr and W, especially in the Cr (up to 705 ppm). The green color of the studied Cr-chalcedonies originates from the element chromium. Taking the possible reserves into account, the hardness, color, massive structures, mineralogical, petrographical and gemological features of Ch-chalcedonies in the region are evaluated together. It is determined that they are suitable for the production of jewelry and ornaments. L1 - http://www.journals.pan.pl/Content/115816/PDF/basibuk-akbudak-gurbuz.pdf L2 - http://www.journals.pan.pl/Content/115816 PY - 2020 IS - No 1 EP - 92 DO - 10.24425/gsm.2020.132551 KW - Ch-chalcedony KW - gemstone KW - green quartz KW - gemology KW - Turkey A1 - Başibüyük, Zeynel A1 - Akbudak, Ilkay Kaydu A1 - Gürbüz, Meltem PB - Komitet Zrównoważonej Gospodarki Surowcami Mineralnymi PAN PB - Instytut Gospodarki Surowcami Mineralnymi i Energią PAN VL - vol. 36 DA - 2020.03.27 T1 - Mineralogical, geochemical and gemological investigation of Artova Ch-chalcedonies, Tokat – Turkey SP - 77 UR - http://www.journals.pan.pl/dlibra/publication/edition/115816 T2 - Gospodarka Surowcami Mineralnymi - Mineral Resources Management ER -