What does aragonite mean?
Aragonite is a naturally occurring mineral composed of calcium carbonate (CaCO₃), chemically identical to the far more abundant mineral calcite but differing in its internal crystal structure — a relationship scientists call polymorphism. Where calcite crystallises in a trigonal system, aragonite forms orthorhombic, often needle-like or fibrous crystals. Although metastable at ordinary surface temperatures and pressures, meaning it gradually converts to calcite over geological time, aragonite is widespread in the biosphere: it forms the nacre of pearls, the shells of many molluscs and corals, and much of the carbonate mud accumulating on modern seafloors. It also precipitates in hot springs and limestone caves. The name derives from Aragón, the Spanish region where notable specimens were first described. The word belongs primarily to the vocabulary of geology, oceanography, and materials science, and its adjective form is aragonitic.
nounA colourless or white orthorhombic mineral form of calcium carbonate (CaCO₃), distinguished from the more common calcite by its crystal structure; it is a major constituent of pearls and the shells of many marine organisms.
- The orthorhombic mineral form of calcium carbonate (CaCO₃), typically found in marine shells, pearls, hot springs, and caves.
"The mother-of-pearl lining the abalone shell is composed of thin layers of aragonite."
"Geologists identified aragonite needles in the sediment, indicating deposition in warm, shallow seas."
"The cave walls glittered with delicate sprays of aragonite deposited by mineral-rich water."
Rarely used in the plural, since aragonite denotes a single mineral species; plural forms appear mainly when referring collectively to distinct varieties or occurrences of the mineral.
"The museum's collection includes aragonites from several famous European localities."
Every pearl you've ever seen is made of aragonite — a mineral named after the Spanish region of Aragón that slowly transforms into ordinary calcite over millions of years.
Reviewed by Deb Chak, Editor. AI-assisted content curated by RJS Tech Solutions LLP.
Etymology of aragonite
The word aragonite was coined in the early nineteenth century after Aragón, the region in north-eastern Spain where fine specimens of the mineral were discovered and first studied. It follows the standard mineralogical convention of naming minerals with the suffix '-ite'. Because the name derives from a place name rather than a classical root, its only true etymological relatives are other terms connected to Aragón itself, such as Aragonese.
Related word forms
How aragonite is actually used
A technical term used mainly in geology, mineralogy, oceanography, and biology. It carries no figurative or informal senses, and outside scientific writing it appears chiefly in discussions of shells, pearls, reefs, and carbonate sediments.
Easily confused with aragonite
Calcite is the more common, trigonal polymorph of the same compound, calcium carbonate, whereas aragonite has an orthorhombic structure and is less stable at surface conditions.