This standard describes methods for the determination of mineralogical phases often present as additives or reaction produced in carbon containing or graphitic refractory products by X-ray Diffraction (XRD) using a Bragg-Brentano diffractometer. It includes details of sample preparation and general principles for qualitative and quantitative analysis of mineralogical phase composition. Quantitative determination of α-Si3N4, β-Si3N4, AlN, aluminium metal, Al4C3, silicon metal, boron carbide and BN are described. The problems encountered with some determinations are highlighted. Additional reduced species present in some refractories could include Al2O3?AlN solid solutions (so called Alons), Si3N4?SiO2 solid solutions and Si3N4?Al2O3 solid solutions (Sialons). The presence of some of these solid solution components will cause problems with both identification and quantification as they are not well defined structures. NOTE For rationalisation of nitrogen containing phases, the total nitrogen content, analysed in accordance with EN 12698-1 is needed.