Lithium deposits occur in various forms, though few are commercially viable. Most commercial lithium operations are based on brines and lithium-bearing minerals, such as spodumene. Spodumene was the principal source of lithium for lithium carbonate production until the 1990s. Since then lithium brines have become a major source of lithium compounds and account for 75% of the current supply. FMC Lithium transitioned to brine-based operations during the mid-1990s.
The following chart summarizes the characteristics of brines and spodumene: