Cobalt
chemical element with symbol Co and atomic number 27
Cobalt is a chemical element; it has symbol Co and atomic number 27. As with nickel, cobalt is found in the Earth's crust only in a chemically combined form, save for small deposits found in alloys of natural meteoric iron. The free element, produced by reductive smelting, is a hard, lustrous, somewhat brittle, gray metal.
Cobalt-based blue pigments (cobalt blue) have been used since antiquity for jewelry and paints, and to impart a distinctive blue tint to glass. The color was long thought to be due to the metal bismuth. Miners had long used the name kobold ore (German for goblin ore) for some of the blue pigment-producing minerals. They were so named because they were poor in known metals and gave off poisonous arsenic-containing fumes when smelted. In 1735, such ores were found to be reducible to a new metal (the first discovered since ancient times), which was ultimately named for the kobold.
Today, cobalt is usually produced as a by-product of copper and nickel mining, but sometimes also from one of a number of metallic-lustered ores such as cobaltite (CoAsS). The Copperbelt in the Democratic Republic of the Congo (DRC) and Zambia yields most of the global cobalt production.
This brief starts where responsible research should: with the source description of “Cobalt” as chemical element with symbol Co and atomic number 27. Everything that follows is an evidence route, not borrowed authority.
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Stable identifiers, scientific names and standards terminology offer the best bridge between this overview and specialist evidence. The source revision retrieved here is dated Sep 23, 2026. The linked authority identifier is Q740. The Library of Congress control number is sh85027513. 1 of 1 selected statements include explicit references; 0 carry qualifiers and 0 use preferred rank. The first chronological checks are 1735.
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This entry incorporates text from “Cobalt” on English Wikipedia. Contributors are listed in the page history. Text is available under the Creative Commons Attribution-ShareAlike 4.0 License. Selected authority identifiers and statements are retrieved from Wikidata under CC0; their references and qualifiers remain part of the verification path.