What does calcite mean?
Calcite is a widely distributed rock-forming mineral composed of calcium carbonate (CaCO₃). It is the chief ingredient of limestone, chalk, and marble, and it also forms spectacular crystals in caves, hydrothermal veins, and hot springs. Pure calcite is colourless or white, though impurities tint it shades of grey, yellow, pink, or blue. One of its most distinctive properties is birefringence — clear specimens split light passing through them into two rays, producing a double image of objects viewed through the crystal. Calcite is also soft (3 on the Mohs scale) and effervesces readily in dilute acids, which makes it easy to distinguish from lookalikes such as quartz. Because it dissolves slightly in acidic water, calcite underlies familiar karst features like caves, sinkholes, and stalactites. For students of geology and collectors alike, it remains one of the most abundant and recognizable minerals on Earth.
nounA common, widespread carbonate mineral consisting of calcium carbonate (CaCO₃), typically white or colourless but occurring in many tints, and the principal constituent of limestone and marble.
- The mineral calcium carbonate (CaCO₃), a major constituent of sedimentary rocks such as limestone and chalk, and of metamorphic marble.
"The cave walls glittered with veins of calcite that caught the lamplight."
"Thin sheets of calcite lined the fissures where groundwater had seeped through the limestone."
"Because Iceland spar is an exceptionally pure form of calcite, it was prized for optical instruments in the nineteenth century."
The plural appears mainly in mineralogical literature when referring to multiple specimens or varieties of the mineral; in general contexts calcite is usually treated as uncountable.
"The museum's drawer contained dozens of calcites from localities around the world."
Clear calcite splits light into two separate images at once — hold it over this page and you'll see double, a trick known since Viking times when it may have served as a 'sunstone' for navigation.
Reviewed by Deb Chak, Editor. AI-assisted content curated by RJS Tech Solutions LLP.
Etymology of calcite
The word 'calcite' derives from Latin 'calx', meaning lime or limestone, combined with the mineral suffix '-ite'. The name was coined in the nineteenth century by the German mineralogist Wilhelm Haidinger. It shares its root with 'calcium', itself named from the same Latin source, and more distantly with words such as 'chalk' that trace back to related origins.
Related word forms
How calcite is actually used
Calcite is primarily used in geological, mineralogical, and scientific contexts; it is not part of everyday colloquial speech. The plural is rarely used except when discussing multiple specimens or varieties.
Easily confused with calcite
Calcite is a calcium carbonate mineral that fizzes in dilute acid and has a hardness of 3 on the Mohs scale, whereas quartz is silicon dioxide with a hardness of 7 and does not react to acid.