ISO 14719:2011 specifies a spectral photometric method with 1,10-phenanthroline for the quantitative determination of Fe2+ and Fe3+ in oxidic raw and basic materials for ceramics, glass and glazes, e.g. feldspar, kaolinites, clay, limestone, quartz refractory materials. ISO 14719:2011 could be extended to other aluminosilicate materials, providing that uncertainty data is produced to support it. However, there might be problems in the decomposition of high-purity alumina and chrome ore samples.
The method is not suitable for reduced materials, such as silicon carbide, graphite-magnesia, etc.