2-D Grain Size Distributions

Abstract

Geomaterials are polycrystalline aggregates—they are composites whose bulk behavior and bulk properties are determined (a) by the physical and chemical properties of the minerals of which they are composed, and (b) by the ‘geometrical properties’ such as shape, size and spatial distribution of the components. As an example, consider a granite and a gneiss: they may be of identical composition, but since their geometry is different, their bulk properties are different too. The aim of image analysis is to quantify the geometry of materials. Our first exercise in the previous chapter (on volume determinations) was aimed at finding a descriptor for a very simple aspect of geometry—the ‘amount’ of a given phase. We used the sum of the cross sectional areas of that phase and determined the volume fraction. We considered the size of the individual cross sections only in so far as we used their statistics to estimate the error, but the focus was on the ‘grand total’ of every phase. In this chapter, we now turn to the size of the individual cross sections.