Abstract:
The sample of agate was recieved from Gondar Polytechnique College, Gondar, which is found in West Belessa, North Gondar, Ethiopia. To identify the silica phases present in the sample of agate that occur in West Belessa, X-ray diffraction (XRD) spectroscopy were performed. Fourier transform infrared (FT-IR) spectra of natural gem agate were performed to identify the nature of water present. Using Flame Atomic Absorption Spectroscopy (FAAS) technique the content of different element composition; (Ca, Fe, Cu, Mn, and Mg) was determined. In order to verify that the sample were indeed agate, some basic preliminary identifications using, a refractometer, heavy liquid method, and ―MOHS HARDNESS PENCILS‖ were carried-out. The physical measurement shows that the hardness of the sample (6.5 to 7), the refractive index is (1.53 to 1.54), and specific gravity of (2.57 to 2.62). The results of the measured values are closely related to literature data which verifies the sample were indeed agate.
For FAAS trace element determination optimization are established by extensive testing of different parameters (temperature, time of drying, reagents volume ratio). It was observed that the white color of agate correlates with the presence of Ca in the sample. FT-IR spectra indicate the presence of both free molecular H2O and defect site silanol Si-OH. X-ray powder diffraction studies of agate that occur in West Belessa shows, strong and moderately intense diffraction peaks for the overlap of -quartz with that of moganite, and the lowest peaks corresponding to single -quartz and moganite.
The characteristic of XRD and FT-IR spectral data for agate sample from West Belessa, North Gondar (Ethiopia) will have a significant contribution in their identification and characterization. The metals level observed in the sample are comparable with their corresponding worldwide reported values.
Key words: Gemstone; Agate; XRD; FT-IR; FAAS; West Bellesa; Ethiopia
