Mafic and Ultramafic Rocks
Mafic and ultramafic rocks, commonly associated with mining operations for nickel, platinum group elements, and chromite, are particularly promising. These rock types are rich in magnesium and calcium silicates, which are highly reactive with CO2. When exposed to air and water, magnesium and calcium silicates can be transformed into magnesium carbonate (magnesite) and calcium carbonate (calcite), locking CO2 in solid form. Recent research in this area has estimated that historical mafic and ultramafic mine waste could sequester as much as 6.5 gigatonnes of CO2 through this mineral carbonation process.