This International Standard specifies the following methods for the determination of the silicon content of chromium ores and concentrates : — method A : molecular absorption spectrometric method, applicable to products having silicon contents from 0,05 to 0,5 % (m/m); — method B : gravimetric method, applicable to pro-ducts having silicon contents from 0,5 to 15 % (m/m). This International Standard should be read in conjunction with ISO 6629.