Tarryn Kim Cawood

Research Scientist
Geological Survey of Canada

The Geology of Critical Battery Metals: A Spotlight on Co in VMS Deposits & Li in Pegmatites

As we move away from a fossil fuel-driven economy, the demand for metals used in energy-dense, rechargeable batteries is increasing. These include cobalt and lithium. Although cobalt is mostly obtained as a by-product from nickel and copper mining, significant amounts also occur in volcanogenic massive sulfide (VMS) deposits, of which Canada has many. However, the primary controls on cobalt distribution in VMS deposits are poorly understood, and deformation and metamorphism may alter this distribution. We show that cobalt can occur in pyrite, which retains its primary composition through greenschist facies metamorphism; and in pyrrhotite, which expels some cobalt during deformation to form cobaltite crystals. 

In contrast, most of the global lithium supply comes from rare metal pegmatites and salars, with pegmatites the most important Canadian source. Our preliminary results confirm that lithium-bearing pegmatites can form directly during anatexis, as well as from fractional crystallization of large bodies of granitic magma.