Mineral carbonation in some cases yields valuable materials. Precipitated calcium carbonate (PCC), for example, has been sold for $320/ton, while ultrapure calcium carbonate obtained from carbonation can yield revenue of > $9000/ton. The annual market for PCC is estimated at $39 billion or roughly 120 million metric tons. The use of mineral carbonation-derived carbonates would only sequester a small fraction of human CO2 emissions.