When was cobalt first discovered by Georg Brandt?
Georg Brandt discovered cobalt in 1735. He proved that the blue color in glass was caused by this metal rather than bismuth. This discovery marked the first element found since the prehistoric era.
Questions about Cobalt
Short answers, pulled from the story.
What is the oldest known use of cobalt in history?
The oldest cobalt-colored glass dates back to the eighteenth dynasty of Egypt between 1550 and 1292 BC. This glass was sourced from cobaltiferous alums found in the Western Oases. The deep blue hue also appeared in Persian jewelry from the third millennium BC.
Which country produces the majority of the world's cobalt supply?
The Democratic Republic of the Congo produces over 80 percent of the world's cobalt supply. The Katanga Province serves as the epicenter of this production. In 2025, the country implemented a four-month suspension of cobalt exports due to oversupply and price decline.
What is the half-life of the radioisotope cobalt-60?
Cobalt-60 has a half-life of 5.27 years. This radioisotope produces gamma rays with energies of 1.17 and 1.33 MeV. It is used for external beam radiotherapy and the sterilization of medical supplies.
What is the atomic number and symbol of cobalt?
Cobalt has the symbol Co and the atomic number 27. It is a hard lustrous gray metal with a specific gravity of 8.9. The element occurs as two crystallographic structures known as hcp and fcc.