Short answers, pulled from the story.
Swedish chemist Georg Brandt (1694-1768) is credited with discovering cobalt around 1735, demonstrating it was a previously unknown element distinct from bismuth and other metals. Cobalt became the first metal discovered since ancient times; all previously known metals, including iron, copper, silver, gold, zinc, mercury, tin, lead, and bismuth, had no recorded discoverers.
The name cobalt derives from the 16th-century German miners' term "kobold ore" (goblin ore), given to a troublesome ore that failed to yield silver and released poisonous arsenic fumes when smelted. The 1868 Grimms' dictionary linked the word to a mountain spirit blamed for stealing silver and leaving hazardous ore behind, though alternative etymologies trace it to a mining bucket or the Greek word for arsenic sulfide.
The Democratic Republic of the Congo produces approximately 75 percent of the world's cobalt supply. In 2024, global production exceeded 300,000 tons, with the DRC accounting for more than 80 percent. The China Molybdenum Company alone contributes roughly 40 percent of world cobalt production from its DRC mines.
Cobalt-60 is used in external beam radiotherapy, sterilization of medical supplies and food (cold pasteurization), industrial radiography to check weld integrity, and density measurements. It produces gamma rays at energies of 1.17 and 1.33 MeV and has a half-life of 5.27 years. Its diminishing potency over time means sources must be replaced periodically, which is a primary reason linear accelerators have largely replaced cobalt machines in modern radiation therapy.
Cobalt is a key component of lithium cobalt oxide (LCO) cathodes, first sold commercially by Sony in 1991. The electric vehicle industry increased cobalt demand five-fold from 2016 to 2020. Battery makers have progressively reduced cobalt content from one-third to one-tenth in cathode formulations, and lithium iron phosphate batteries with no cobalt at all surpassed ternary cobalt batteries in installed capacity in 2021.
Child labor has been documented in artisanal cobalt mines in the Democratic Republic of the Congo, which supplied between 17 and 40 percent of DRC production as of 2016. Apple Inc. stopped buying from implicated suppliers on the 3rd of March 2017, and in December 2019 International Rights Advocates filed a lawsuit against Apple, Tesla, Dell, Microsoft, and Alphabet. In 2024 a court ruled that suppliers facilitated forced labor but found the US tech companies not directly liable.