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Carbonado
Carbonado, also known as black diamond, is an opaque black natural polycrystalline diamond found only in Brazil and the Central African Republic, with no known source rock.
Carbonate compensation depth
The carbonate compensation depth (CCD) is the ocean depth at which the supply of calcium carbonate sinking from the surface equals its dissolution at the seafloor.
Carbonate minerals
Carbonate minerals are minerals containing the carbonate ion CO3, combined with metals such as calcium and magnesium; calcite and dolomite make up over 90 percent of them.
Carbonatite
Carbonatite is a rare igneous rock composed mainly of carbonate minerals, derived from Earth's mantle, and the primary source of niobium and light rare earth elements worldwide.
Carboniferous
The Carboniferous, or Carboniferous Period, is a geologic period of the Paleozoic Era from 358.9 to 298.9 million years ago, named for its coal-bearing swamp rocks.
Caribbean Plate
The Caribbean Plate is a small, mostly oceanic tectonic plate that carries the Caribbean Sea and Central America between the North American and South American plates.
Carl Young (storm chaser)
Carl Young, full name Carl Richard Young, was an American meteorologist and storm chaser with the TWISTEX team, killed by the El Reno, Oklahoma tornado in 2013.
Carmen de Andacollo
Carmen de Andacollo is an open-pit copper and gold mine in the Coquimbo Region of central Chile, 90% owned by Teck Resources and adjacent to the town of Andacollo.
Carnelian
Carnelian, also called Corniola, is a translucent red to reddish-orange variety of chalcedony, a microcrystalline quartz colored by iron oxide, prized since antiquity for seals and beads.
Carnian pluvial episode
The Carnian pluvial episode, or Carnian pluvial event, was an interval of warming and increased rainfall in the Late Triassic, about 234 to 232 million years ago.
Carol Kirkwood
Carol Kirkwood, born Carol Anne MacKellaig in 1962, is a Scottish broadcaster who presented the weather on BBC Breakfast from 2010 until retiring in 2026 after 28 years at the BBC.
Carol Lake (mine)
Carol Lake is an open-pit iron ore mine near Labrador City, Newfoundland and Labrador, operated by the Iron Ore Company of Canada and producing continuously since 1962.
Carr Fire tornado
The Carr Fire tornado, or Carr Fire whirl, was a tornado-strength fire vortex that formed near Redding, California, on July 26, 2018, with 143 mph winds.
Carrapateena mine
Carrapateena mine is an underground copper, gold, and silver mine in South Australia's Gawler Craton, about 160 kilometers north of Port Augusta, discovered in 2005 and operated by BHP.
Carrara marble
Carrara marble, also known as Luna marble, is a white sculptural stone quarried in the Apuan Alps of Tuscany, Italy, since Roman times and famously favored by Michelangelo.
Cartography
Cartography, also known as map making or cartology, is the art, science, and technology of making and using maps, practiced since ancient Babylonian clay tablets.
Casa Berardi Gold Mine
The Casa Berardi Gold Mine is a gold mine in the Abitibi region of northwestern Quebec, first opened in 1988 and owned by Orezone Gold Corporation since 2026.
CASA X-band radar network
The CASA X-band radar network is a system of small, short-range Doppler weather radars that scan the lowest atmosphere collaboratively, developed by NSF's CASA engineering research center.
Cascade Volcanoes
The Cascade Volcanoes, also known as the Cascade Volcanic Arc, are the active volcanoes of the Cascade Range, a 800-mile chain from northern California to southern British Columbia.
Cascadia subduction zone
The Cascadia subduction zone, also known as the Cascadia fault zone, is a 1,100 km megathrust off the Pacific Northwest, where the Juan de Fuca Plate subducts beneath North America.
Cassiterite
Cassiterite is a dense, hard tin oxide mineral, SnO₂, and the principal ore of tin, found in granite-related veins and in placer deposits formed as they weather.
Caswellsilverite
Caswellsilverite is a rare sodium chromium sulfide mineral with the formula NaCrS₂, approved by the International Mineralogical Association in 1981 and known almost entirely from enstatite-rich meteorites, first described from the Norton County meteorite in Kansas.
Catalão (mining complex)
The Catalão mining complex is a group of open-pit niobium and phosphate mines operated by CMOC Brasil at the Catalão I and II carbonatite complexes in southeastern Goiás, Brazil.
Catastrophism
Catastrophism is the geologic theory that sudden, high-energy events such as floods, eruptions, and asteroid impacts shape Earth's history, formulated by Georges Cuvier around 1800.
Catatumbo lightning
Catatumbo lightning, known in Spanish as Relámpago del Catatumbo and called the Maracaibo Lighthouse, is a persistent, nearly nightly lightning display over Lake Maracaibo in Venezuela.
Cathaysia
Cathaysia: a Late Paleozoic East Asian biogeographic realm (Cathaysia flora, 华夏植物群; Cathaysialand of South China, Indochina, North Qiangtang) and an extinct Permian productid brachiopod genus, distinct from the conifer Cathaya.
Cation-exchange capacity
Cation-exchange capacity (CEC) is a soil science measure of the negatively charged sites on soil and clay surfaces that reversibly hold nutrient cations such as calcium, magnesium, and potassium.
Cauchari-Olaroz
Cauchari-Olaroz is a lithium brine mining operation in Jujuy Province, northwestern Argentina, producing battery-grade lithium carbonate; it was commissioned in 2024 with a capacity of 40,000 tonnes per year.
Cenomanian
The Cenomanian is the lowest stage of the Upper Cretaceous, spanning roughly 100.5 to 93.9 million years ago; it was defined by Alcide d'Orbigny near Le Mans, France.
Cenozoic
The Cenozoic, also called the Age of Mammals, is the current geological era. It began 66 million years ago with the extinction that ended the Mesozoic.