Study is made for the first time on morphological peculiarities of microstructure of three samples from the unbroken marker ash layers of the Shiveluch volcano. In this paper we give the qualitative analysis of tephra structure, i.e. size and shape of particles and type of microstructure, describe structural relationships between deposit components, etc. and make the quantitative analysis of porosity of Sh2 and Sh1 tephra at magnification of 200 and 1,000. Hollow globules of volcanic glass were found for the first time in Sh2 ashes.