Gümenek (Komana) ve Döllük Köyleri (Tokat) Civarındaki Kalsedonların Petrografik ve Gemolojik İncelenmesi

Abstract

The study area covers the Komana-Döllük Village and its vicinity in the Central Black Sea Region, just west of Tokat. Tokat is very rich in semi-precious stones and has good quality jasper, wood opal, petrified wood, chalcedony, agate, chrysoprase, quartz, agate etc. in the region. There are very high-quality chalcedony and agate formations in Turhal-Tokat and Almus line. In this study, it is aimed that the geological features of the Gümenek and Döllük villages in the western part of Tokat Province and interrelations between the chalcedonies and geological units were investigated. Paleozoic metamorphic rocks of the Tokat Massif, Cenozoic volcano-sedimentary sequence and Quaternary clastics cropped out in the study area. The Tokat Massif, which forms the basement of the study area, is metamorphosed in the low grade greenschist facies and is represented by metabasalt, metagreywacke, micaschist, crystallized limestone, marble, amphibolite and slightly blueschists. In the west of the area, the Middle Eocene volcano-sedimentary rocks unconformably cover the Tokat Massif. Chalcedony formations are observed along a fault zone close to the D-B trending line passing through the metamorphic units of the Tokat Massif. The chalcedonies were formed mostly in the cracks, fractures and cavities of the recrystallized limestones, which had a more fractured and brecciated structure due to faults along a line approximately 25 m perpendicular to this fault zone. The colour of the chalcedonies is mostly light blue and close to white, dark blue and greyish blue. Usually symmetrical and asymmetric vessel filling, gap filling, geoid, banded and lacy structure is observed. Parallel to each other, several mm thick banded structures are common from the outside of the void and some cavities are filled with coarse crystalline quartz. Chalcedony species consist of microcyristalline quartz. The chalcedony samples collected during field studies were classified in Selçuk University SÜKOP Gemstone Application and Research Center, and then they were cleaned, cut, etched and polished for plate, slice, ball and cabochon production. The obtained polished products were used to production of rings, necklaces, earrings, brooches, bracelets, rosaries, keyrings and nameplates. As a result, the chalcedony of the region provides many criteria such as structure, texture, hardness, variety of colours, polishing, light reflection and durability and can be used as a gemstone. If the chalcedony potential of the region is assessed and evaluated by appropriate production methods, significant contributions can be made to the promotion and economy of the region.