Describes a gravimetric method for determining loss of ignition and classical (wet analysis) and spectrophotometric methods of analysis of dolomites and magnesites used as refractory materials. Includes determination of oxides of silicon, iron, titanium, manganese, chromium, aluminium, calcium, magnesium and boron (for magnesites only). Sodium, potassium and lithium oxides are determined by flame photometry. Typical compositions of dolomites and magnesites are contoured in table form together with a statement on repeatability of the analyses.