Spectroscopic Studies of Natural Gem- Agate in Sedimentary and Volcanic host rocks from (Bellesa, Addis zemen and Bure), in Amhara National Regional State (Ethiopia)

The representative samples of gem-agate were collected from Bellesa (North Gondar), addis zemen (South Gondar) and Bure (West Gojam). The samples were identified and characterized by different physical property measuring devices and advanced spectroscopic techniques. In order to verify that the samples were indeed agate a refractometer, heavy liquid method and "MOHS HARDNESS PENCILS" were used. The performed physical analysis shows that the hardness value of Addis zemen and Bure are in the range of 6.5-7 and that of Bellesa is 7 while the refractive index and specific gravity of both agate samples are similar and in the range of 1.53-1.54 and 2.4-2.7 respectively. The XRD and FTIR spectral data of agate samples from three zones of the Amhara National Regional state have a significant contribution in their identification and characterization. The content of different trace elements (Ca, Mg, Fe, Cu, Cd and Mn) was analyzed by FAAS technique. Generally the investigated agate samples by using FT-IR show a broad band around 4000-2500 cm-1, for the O-H stretch of water molecule is around 3440 cm-1 , around 3585 cm-1 structural defect of silanol group and around 1084 cm-1 for Si-O stretch and at low frequency 694 cm-1 indicates the O-H stretch of silanol group.