CO2 solubility has a slight negative temperature dependence in olivine melilitite at 30 kb with 9% CO2 dissolved at 1,450 °C, 8.5% at 1,550 °C and 8.3% at 1,650° C. CO2 is dissolved as the carbonate molecule (CO32−) only. Feldspar melts (albite-anorthite) dissolve much less CO2 at 30 kb (around 2%) with a slight increase with increasing anorthite content. A CO2 absorption peak in infrared spectra of albite-rich glasses diappears in favour of the CO32−peak with increasing anorthite content. It is inferred that CO2 was present as CO32−in albite-rich melts also, but reverts to CO2 during quenching because of bonding differences related to Ca2+ and Na+ in the melts.