Aragonite
Species
Common · CaCO₃
A polymorph of calcite that forms at lower temperatures and higher pressures. Metastable at surface conditions and slowly converts to calcite over geological time. Many shells and coral skeletons are built of it, which makes it a major part of marine sediments.
Identity
- Formula
- CaCO₃
- Chemical class
- Carbonate
- Part of
- Mother of Pearl, Pearl
- Mineral group
- Cerussite
- Also known as
- Flos ferri (coralloid variety)
Crystallography
- Crystal system
- Orthorhombic
- Habits
- Prismatic, Tabular, Acicular, Massive
- Fracture
- Subconchoidal
Physical properties
- Mohs hardness
- 3.5
- Density
- 2.93 g/cm³
- Luster
- Vitreous, Resinous
- Colors
- colorless, white, gray, yellow, blue, violet
- Streak
- white
- Transparency
- Transparent, Translucent
Geology
- Origins
- Sedimentary, Hydrothermal
- Host rocks
- Limestone and chalk
- Associated minerals
- Calcite, Gypsum, Sulfur, Celestine
- Found in
- Limestone, Travertine
- Geography
- worldwide
Classification
- Rarity
- Common
- Gem quality
- No
Sources
- M. Pasero and others, IMA Commission on New Minerals, Nomenclature and Classification, The New IMA List of Minerals, updated September 2026. International Mineralogical Association (CNMNC), 2026.
- Aragonite. Mindat.org (Hudson Institute of Mineralogy).
- J. W. Anthony, R. A. Bideaux, K. W. Bladh, M. C. Nichols, Aragonite. Mineral Data Publishing, Handbook of Mineralogy, 2001.
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