The Theory of Thin-Section Analysis

Abstract

A thin-section analysis provides an unbiased estimate of the areal composition of the surface measured. A randomly chosen area provides an unbiased estimate of composition by volume. Orientation of the rock or of the thin section with regard to some structure element of the rock may improve or reduce the efficiency of the sampling but will not in itself bias the result. The tradition that only unoriented or weakly oriented rocks are suitable for modal analysis is unfounded.