What are rocks and minerals, anyway? Minerals are naturally occurring inorganic compounds ("non-living material"). Rocks are extensive mineral bodies composed of one or more minerals in different amounts, which form part of the earth's crust. When we separate rocks and minerals by their colour, texture and luster, we are classifying them. This helps us to understand how rocks and minerals are similar and how they are different. Rocks and minerals are valuable natural resources that we should protect.