Research has been published over the past few decades on the possible use of thorium in various nuclear power reactor types. Therefore, it is worthwhile to analyse the supply situation for additional thorium generated as a by-product of commodities produced for non-nuclear purposes. This publication provides information on the natural occurrence of thorium, the geology of thorium and potential thorium resources. It presents an overview of exploration and evaluation of projects, including studies for project feasibility, principles of ore processing, as well as market and production scenarios. Selected examples of deposits containing thorium as a potential co-product or by-product are presented as case studies.