Kaydu Akbudak, İlkay; Gürbüz, Meltem; Başibüyük, Zeynel; Hatipoğlu, Murat; Öztüfekçi Önal, Ayten; İşler, Fikret

The corundum is found in the rocks of the Berit metaophiolite in Eastern Anatolia, near Doğanşehir a province of Malatya. Metaophiolitic rocks consist mainly of garnet metagabbro, granulite, amphibolite, mylonitic amphibolite, garnet amphibolite, amphibole schist, pyroxenite, mylonitic pyroxenite, orthopyroxenite, harzburgite, serpentinized dunite and diorite units. Corundum occurrences are mostly found in pyroxenites, amphibolites, peridotites and granulites. Their colors change in range between reddish pink, pink and light pink. They are usually in structure of translucent, vitreous and sometimes cracked. They are seen scattered or clustered together inside the rocks in which they are found. The size of their crystals ranges from 0.5 cm to 10 cm and their euhedral crystals are observed in pseudohexagonal form. As a result of the petrographic examinations, it was observed that pyroxene, amphibole, garnet and plagioclase minerals accompanied with the corundum. The samples of the rocks containing the corundum has qualifications which will be as an object of gemstone and ornament by means of cutting and shining. Large specimens of corundum can be processed alone. Samples, being as scattered and small granules inside the rock can be processed together with the host rock. In the processed samples, it was obtained patterns like the samples of corundum with zoisite which were in great demand in the world gemstone market.

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GuRBuZ, Meltem; Önal, Ayten Öztüfekçi; Basıbüyük, Zeynel; Akbudak, Ilkay Kaydu; İşler, Fikret

Yamadağ Volcanics which is one of the examples of the Late Miocene volcanism in Eastern Anatolia covers largeareas within the boundaries of Arguvan county of Malatya. The gemstones, subject of this research range from afew centimeters to about 30-40 cm in size and are formed in the cavities of the basalts beonging to Yamadağvolcanics. These gemstones seem to have formed as veins extending in east-west direction and consist of opal (opal-CT) and chrysocolla. Opal formations have various colours such as white, brown, yellow and greenish, while chrysocolla formations are bluish-greenish in color. both opal and chrysocolla are of massive type and their freshsurfaces display waxy luster. Mineral paragenesis and formation conditions of gemstones and are determined byapplying XRD, SEM, FT-IR techniques. ICP-MS technique is used for the determination of the geochemicalcompositions. The gemological characteristics are identified via cabochon and facet cut techniques by usingdiamond coating blade, sintered diamond abrasive discs and polishing machine. Opals are usually composed oftridymite minerals, also in some cases quartz and cristobalite minerals accompany the tridymite minerals. The EDXmeasurements reveal, enrichment of Fe and Al in opals, and of Cu in chrysocolla. The ICP-MS measurements, in chrysocollas reveal, enrichments in LIL elements such as Ba, Sr and in HFS elements such as U. Consequently,gemological studies show that the chrysocolla and opals in study area, which have waxy luster and massivestructure, are suitable for utilization as a gemstone due to its color, hardness, durability, homogeneous distributionof color and processability

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