The contents of K2O and MgO are 1.81–4.12% and .91–3.7%, respectively. The Fe2O3 content of carbonaceous marls (.85–12.96%) is reasonably larger than the FeO content (.83–1.26%). The contents of other oxides, such as MnO, Na2O, P2O5, and TiO2, are significantly less than 1.%. Blake Johnson is an Iowa State graduate...
- 2022-11-13
