This International Standard specifies two methods for the determination of chromium in manganese ores: - Method I: diphenylcarbazide photometric method, which is applicable to manganese ores having chromium contents less than 0,1 % (m/m); - Method II : silver persulphate titrimetric method, which is applicable to manganese ores having chromium contents greater than 0,1 % (m/m). This International Standard should be read in conjunction with ISO 4297.