Linnaeite is a cobalt sulfide mineral with the composition Co<sup>+2</sup>Co<sup>+3</sup><sub>2</sub>S<sub>4</sub>. It was discovered in 1845 in Västmanland, Sweden, and was named to honor Carl Linnaeus (1707âÂÂ1778).
Linnaeite forms a series with polydymite, Ni<sup>+2</sup>Ni<sup>+3</sup><sub>2</sub>S<sub>4</sub>. Linnaeite is found in hydrothermal veins with other cobalt and nickel sulfides in many localities around the world.