The particles that make up rocks are called minerals. The minerals occur naturally and have a homogenous chemical composition. They can be formed from a single element or from a compound whose atoms are allowed to come together in an ordered atomic arrangement process known as crystallization. Minerals are found in different types of rocks in the earth, such as
metamorphic rock, each with their own unique texture. There are a variety of techniques used by geologists to determine the mineral type and to evaluate its properties. Examples of some criteria analyzed are the shape, density, flammability, magnetism, electrical properties and hardness (relative scale with diamond being hardest (hardness 10) and talc being the softest (hardness 1)).
Rocks and minerals are essential in our lives. In fact, the world would be a completely different place if we did not know how to mine, process and use minerals. For example, gravel and clay are used for construction of buildings, road and bridges and also brick manufacture. There are many technical uses of minerals such as silicon wafering in which silicon boules are grown (pulled) from a molten state from a seed crystal and are sliced into very thin wafers, upon which complex integrated circuits can be etched. Also, the diamond for example, is the hardest natural substance on earth and it is used to cut, grind, and polish most hard substances as well as provide individuals with beautiful pieces of jewelry. Of over 2000 different types of minerals, less than 100 are considered beautiful or durable enough to be used as gemstones. Of these, only 20 are commonly used in jewelry. “Minerals” as referred to in nutrition, are elements mostly available as ions that are essential for the function of living organisms (see our section “Elements and Ions”). This section contains structures of common minerals.