The earth’s crust is composed of rocks. Rock is a mineral mass of a more or less uniform composition. It may consist of a single mineral (monomineralic) or of several minerals (polymineralic). A mineral is a natural body, homogeneous in chemical composition and physical properties. Further minerals are the products of physical and chemical processes occurring in the earth’s crust.
Monomineralic rocks are quartz sand, pure gypsum and magnesite, and the polymineralic ones are granite, basalt and porphyries.
Natural rock materials are widely used for building purposes owing to their universal occurrence and physical and mechanical properties. They are used as mined materials, e.g., gravel, sand, or mechanically ...