Some improvements of quantitative analytical techniques of volcanic glass shards by means of energy dispersion X-ray microanalyzer

The results of quantitative chemical analysis on volcanic glass shards are discussed with examination of analytical technique. The apparatus being used is Oxford Link ISIS energy dispersion X-ray microanalyzer (EDS) with JEOL JSM-5400 scanning electron microscope (SEM). Some analyzed samples are AT ash in the Sadohara-cho, Miyazaki Prefecture and Hirano tephra in the Nomura-cho, Ehime prefecture. The results show that (1) The available finest 15kV acceralation voltage, 4.00×10^^<-10>A beam current of exposed electron beam and 30 seconds of acquisition live time, (2) the volcanic glass shards show low K_2O contents in the edge, which is changed in quality, (3) analytical technique is that the use of polished internal surface of glasses until a thickness of glass shards become about half, (4) The data of glass shard should be checked and selected by H_2O contents