Published online by Cambridge University Press: 14 March 2018
After CO2 and C are allocated to carbonates and carbonaceous matter, FeO and MgO are allocated to a hypothetical “average” chlorite of composition 12(Fe, MgO). 3Al2O3. 7SiO2. 10H2O, K2O is allocated to muscovite, remaining Al2O3 to kaolinite, remaining SiO2 to quartz, calculated hydroxyls usually agree well with H2O+. Calculated mineral analyses agree well with practical assessment and thermal expansion curves. Chlorite and chlorite-illite are known to occur (X-rays) in this series of clays.