Mineral

Minerals are substances that are formed naturally in the Earth. Minerals vary in composition, from pure elements and simple salts to very complex silicates with thousands of known forms. In contrast, a rock sample is a random aggregate of minerals and/or mineraloids, and has no specific chemical composition. Most of the rocks of the Earth's crust have quartz (crystalline SiO₂), feldspar, mica, chlorite, kaolin, calcite, epidote, olivine, augite, hornblende, magnetite, hematite, limonite and a few other minerals. Some minerals, like quartz, mica or feldspar are common, while others have been found in only a few places in the world. The largest group of minerals by far is the silicates (most rocks are ≥95% silicates), which are made largely of silicon and oxygen, also with ions of aluminium, magnesium, iron, calcium and other metals.

Rocks are made of minerals. Minerals are usually solid, inorganic, have a crystal structure, and form naturally by geological processes.^[1]

The study of minerals is called mineralogy.^[2]

A mineral can be made of single chemical element or more usually a compound. There are over 4,000 types of known minerals.^[3] Two common minerals are quartz and feldspar.

1. ↑ L.B. Railsback Definitions [1] Archived 2013-03-02 at the Wayback Machine and [2] Archived 2012-09-15 at the Wayback Machine
2. ↑ Dana J.D. Hurlbut C.S. & Klein C. 1985. Manual of mineralogy. 20th ed, Wiley.
3. ↑ International Mineralogical Association IMA/CNMNC List of Mineral Names Archived 2013-06-26 at the Wayback Machine (PDF 1.8 MB;)