Petrographic study of silica bearing rocks from Assam, India

Abstract

Silica bearing rock samples collected from various locations of the rock from Bihubar, Assam, India were studied using XRD, FT-IR and chemical analysis for assessing the durability of these rocks used for different purposes like building and road constructions. XRD patterns of the rock samples-reddish coloured rock variety (2QPR ) and white coloured rock variety (5QRS) showed that the samples contained the amorphous and crystalline materials, the former being the major one in both the samples. Both the samples contained α-quartz as the major phase with rutile, albite, calcite and illite-2M₁ for 2QPR and

muscovite-2M₁, illite and analcime for 5QRS as the minor phases. Microstrains and crystallite sizes of α-quartz associated in the rock samples were derived by using Fourier and integral methods. FT-IR and chemical analysis are also included to supplement the result obtained from XRD method. The presence of the clay minerals and microstrains in both the samples indicate the possibility of degradation of the rocks in environment and hence ultimately effects its durability in utilization.