What Is Cobalt?
QUICK ANSWER
Cobalt is a chemical element with atomic number 27 and the symbol Co. It's a hard, silvery-gray transition metal with a slight bluish tinge that's magnetic at room temperature. Cobalt is essential to many lithium-ion batteries, superalloys for jet engines, and the deep blue pigments used in ceramics for centuries.
Cobalt is the metal behind two very different products: the rechargeable battery in your phone and the deep blue glaze on ancient pottery. The same element has been used to color glass and ceramics since Persian and Egyptian times, but modern demand has exploded because of its role in electric vehicle batteries. The ethical sourcing of cobalt, especially from the Democratic Republic of Congo, has become a major industry concern.
Where is cobalt on the periodic table?
Cobalt has atomic number 27, the symbol Co, and sits in group 9 of the periodic table among the transition metals, between iron and nickel. Its atomic mass is about 58.9. Only one stable isotope exists naturally, Co-59. Several radioactive isotopes have important applications, including Co-60, used in cancer radiotherapy and industrial radiography. Cobalt was first isolated in 1735 by Georg Brandt, the first new metal discovered since ancient times. The name comes from the German Kobold meaning 'goblin,' a reference to ore that miners blamed for poisoning them.
What are the properties of cobalt?
Cobalt is a hard, lustrous, silvery-gray metal with a slight bluish tinge. The melting point is 1,495°C and density is 8.86 g/cm³. Cobalt is one of only four elements magnetic at room temperature, alongside iron, nickel, and gadolinium. It retains magnetism at higher temperatures than iron (up to 1,121°C), which makes cobalt alloys valuable in high-temperature magnetic applications. Cobalt is relatively unreactive in dry air but reacts slowly with oxygen at high temperatures. The metal is found primarily as a byproduct of nickel and copper mining.
What is cobalt used for?
Lithium-ion batteries are the largest growing use, with cobalt in cathode materials providing high energy density and stability. Electric vehicles, smartphones, and laptops all depend on cobalt-containing batteries. Superalloys with cobalt tolerate the extreme heat in jet engines, gas turbines, and rocket nozzles. Magnets containing cobalt remain powerful at high temperatures where neodymium magnets fail. Cobalt blue (cobalt aluminate) has colored glass and ceramics for centuries. Cobalt-60 isotopes treat cancer through radiation therapy and sterilize medical equipment. Cobalt catalysts help refine petroleum products.
Why is cobalt sourcing controversial?
About 70% of the world's cobalt comes from the Democratic Republic of the Congo, where mining conditions have been linked to child labor, dangerous working conditions, and human rights abuses. As demand for electric vehicle batteries has exploded, scrutiny of cobalt supply chains has intensified. Major manufacturers are pursuing several approaches: certifying ethical sources, recycling cobalt from old batteries, and developing battery chemistries that use less cobalt or none at all. New nickel-rich and lithium-iron-phosphate cathode designs are gradually reducing per-vehicle cobalt requirements.
Cobalt powers the modern world and colors its pottery. The same metal that made Persian blue glaze possible is now essential to electric vehicle batteries, jet engines, and cancer treatment. Few elements span such a range of applications, and few face such pressing questions about how to source ethically going forward.
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