Types of minerals

Minerals make up most of the earth and are an important part of our everyday life.

Minerals are simply naturally occurring substances which have a crystalline structure. There are many thousands of minerals recognised, but only about 30 are most common.

Classification

Minerals, being natural chemicals, are classified according to their chemistry and crystal form.

A basic classification for minerals is:

  • Native elements. eg. Gold, Silver, Mercury, graphite, diamond.
  • Oxides. eg corundum (incl. sapphire), hematite, spinel.
  • Hydroxides. eg. Goethite, brucite.
  • Sulfides. eg. Pyrite, galena, sphalerite.
  • Sulfates. eg. Baryte, gypsum.
  • Carbonates. eg. Calcite, magnesite, dolomite.
  • Phosphates. eg. Apatite, monazite.
  • Halides. eg. Fluorite, halite (rock salt).
  • Silicates (most common)
  • Orthosilicates. eg. Garnet, olivine.
  • Ring silicates. eg. Tourmaline, beryl.
  • Chain silicates. eg. Pyroxenes, amphiboles.
  • Sheet silicates. eg. Muscovite mica, biotite mica, clay minerals
  • Framework silicates. eg. Quartz, feldspars, zeolites

Identification

Identifying common minerals can usually be accomplished by examining a hand specimen. Minerals have distinct physical properties such as specific gravity, streak, and form which can easily distinguish the major rock-forming minerals.

More detailed examination of minerals can be undertaken by examining a microscope thin section of a rock or mineral. The optical properties of each mineral are unique, and minerals can be readily identified in thin section. More accurate analysis of minerals can be undertaken with a variety of analytical machines. These include X-ray diffraction, microprobe analysis, mass spectrometry and more. The science of minerals is called Mineralogy.

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