Cobalt canyon in the side of a mountain. The firm Calera Mining Company started production at the site. The stable form of cobalt is produced in supernovas through the r-process. It comprises 0.0029% of the Earth's crust. Free cobalt (the native metal) is not found on Earth because of the oxygen in the atmosphere and the chlorine in the ocean. Both are abundant enough in the upper layers of the Earth's crust to prevent native metal cobalt from forming. Except as recently delivered in meteoric iron, pure cobalt in native metal form is unknown on Earth. The element has a medium
Cobalt sulfide Cobalt sulfide Cobalt sulfide is the name for chemical compounds with a formula CoS. Well-characterized species include minerals with the formula CoS, CoS, CoS, and CoS. In general, the sulfides of cobalt are black, semiconducting, insoluble in water, and nonstoichiometric. Cobalt sulfides occur widely as minerals, comprising major sources of all cobalt compounds. Binary cobalt sulfide minerals include the cattierite (CoS) and linnaeite (CoS). CoS (see image in table) is isostructural with iron pyrite, featuring disulfide groups, i.e. CoS. Linnaeite, also rare, adopts the spinel motif. The CoS compound is known as a very rare cobaltpentlandite (the Co analogue of