Structural investigations of a series of petrified woods of different origin

Since the investigations on petrified wood performed so far have not proved the assumption that the ring structure is coupled to the changes in the cr ystalline form of silica, attention was paid to other possible reasons. Usi ng small angle X-ray scattering methods we determined the Pored curves and pore size distributions for five different samples of petrified wood, of di fferent origin. We observed clear porosity differences in different samples . In addition, the normal X-ray diffractometric measurements were carried o ut, which gave a totally uniform image of the crystallographic structure of all the samples. All of them were made of pure alpha -quartz. The differen tiation of rings in dark and bright zones should be put down to the changes in porosity rather than to other factors. The pores seem to be much more c oncentrated in those ring locations, which correspond to the original dark wood positions in living wood. (C) 2001 Elsevier Science B.V. All rights re served.