Study on Chalcedony Gemstone from Kolluru Area, Guntur District, Andhra Pradesh, India

ABSTRACT Twenty three mineral samples are collected from the Kolluru area, Guntur District, Andhra Pradesh, India, for their identification. Fifteen samples are subjected to chemical analyses to estimate the major oxides using WD-XRF and EPMA. The trace elements are measured using ICP-MS. Based on the physical and chemical properties, the samples are identified as Chalcedony gemstone. Using the colour, luster and predominance of SiO2 composition, four varieties, i.e., Carnelian, Agate, Jasper and Plasma are differentiated. Keywords: Chalcedony gemstone, oxides, trace elements, crystal chemistry.