Dimorphism (crystallography)

Dimorphism is the property of some minerals to exist in two different crystal systems, while still having the same chemical formula. A common example is calcium carbonate (CaCO3), which exists as trigonal calcite or orthorhombic aragonite in nature. A mineral's dimorph is the mineral that it is dimorphic with.[1][2] Dimorphism is not to be confused with allotropy, which refers to a difference in crystal structure of pure elements.

Doubly terminated calcite crystal.
Aragonite from Spain.

Trimorphism & Polymorphism

Trimorphism is the term used when a mineral has a total of three dimorphs,[3] while the term polymorphism is used when there are four or more. Silica, SiO2, is an example of this, being found in nature as quartz, tridymite, cristobalite, coesite, and stishovite.[4] Pleomorphism is a synonym of polymorphism.[4]

See also

References
  1. "Definition of dimorphism - mindat.org glossary". www.mindat.org. Retrieved 2016-10-23.
  2. "Dimorphous - Minerals.net Glossary of Terms". www.minerals.net. Retrieved 2016-10-23.
  3. "Definition of trimorphism - mindat.org glossary". www.mindat.org. Retrieved 2016-10-23.
  4. "Definition of polymorphism - mindat.org glossary". www.mindat.org. Retrieved 2016-10-23.
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