CHEMICAL AND MINEROLOGICAL CHARACTERIZATIONS OF THE OLTU STONE (TURKISH BLACK AMBER), ERZURUM, TURKEY

Abstract

Oltu stone carving is being done in an extensive scale in Oltu and Erzurum and a bit in Ardahan which are located in the eastern part of Pontide belt in Turkey. The Permo-Carboniferous, Jurassic-Cretaceous, Tertiary and Quaternary-aged geological units outcrop in this region. The Oltu stone deposit with Jurassic-Cretaceous is a flych character sequence, including limestone, sandstone inter bedded with volcanic, sandstone, marl and clay stone levels. The Oltu stone dominantly consists of carbon and it includes resinite, semifusinite and fusinite. It is found in thickness of a few cm in maximum in a layer of 70-80 cm. The most attracting character of it is its being very soft when carved out and preserving its softy if not contacted with air and becoming hard when contacted with air. The colours of Oltu stone are black generally, sometimes dark brown, rarely grey and green. Its production is carried out by non-technological methods in the underground galleries.