Introduction

Observations in three and two dimensions

Many different analytical methods have been applied to quantifying the textures of rocks, but all start with observations of rocks either in three or two dimensions. In this chapter I will start with general analytical methods that apply to the determination of many different textural parameters. Methods specific to a particular textural parameter will be discussed later in the relevant chapters. It should be remembered that different methods can be combined within a study. This can validate data acquired by innovative methods and also extend the range of grain sizes that can be quantified (Figure 2.1). Some methods that I will describe are used widely (e.g. transmitted light microscopy) whereas others are discussed here because I think that they have potential for future textural studies (e.g. Nomarski imaging). Researchers do not always choose their analytical method in the most logical way: here I want to survey the field to show what others have done. However, researchers, especially students, should never forget that a lot can be done with little equipment – my first crystal size distribution study used a microscope, camera, ruler and protractor (Higgins, 1991).

The texture of many different objects or parts of objects in a rock can be described: it is important to specify at the start what you want to examine. For instance, if a crystal is fractured then the size of the fragments or the size of the original crystal can be measured.