Observation and classification have helped us understand the great variety and complexity of Earth materials.  Minerals are the naturally occurring inorganic solid elements, compounds, and mixtures from which rocks are made.  We classify minerals on the basis of their chemical composition and observable properties. Rocks are generally classified by their origin (igneous, metamorphic, and sedimentary), texture, and mineral content. Rocks and mineral help us understand Earth’s historical development and its dynamics. They are important to us because of their availability and properties. The use and distribution of mineral resources and fossil fuels have important economic and environmental impacts. As limited resources, they must be used wisely.