Lithium dissolved in subsurface salt-water, concentrated by evaporation rather than mined as rock.
Underground reservoirs of salty water with dissolved lithium compounds, typically found in salt flats (salars) in South America. Brine extraction involves pumping to surface evaporation ponds, offering lower production costs than hard rock mining but longer development timelines.
Brine and hard-rock lithium are different businesses. Brine has lower operating costs and much longer ramp-up, and its grades are quoted in milligrams per litre rather than as a percentage, so the two cannot be compared directly.
Watch flow rates and aquifer characteristics as closely as grade — the ability to actually pump the brine decides the project.