Summary: For the estimation of the properties of calcium-iron olivines in ironore sinters, synthetic mixtures of CaO, FeO, and SiO₂ were prepared and melted; the obtained olivines were then examined microscopically and by X-ray powder method. The investigations allowed to state, that with the increase of the basicity of sinters, the relation of Fe : Ca in olivines decreases, which causes the change of their physical, optical, and röntgenometric properties.