Powders of irizing and non-irizing plagioclases (labrador and albite) were studied using a small-angle X-ray camera. The obtained curves of X-ray small-angle scattering in the coordinates "scattering intensity" - "backspace vector modulus" on a double logarithmic scale reveal a pronounced rectilinear dependence. The fractal dimensionality for these curves is D=2. This indicates that the particles of the studied plagioclase powders have a flat surface in a wide range of sizes from 10 to 150nm. It is assumed that during mineral grinding, fractures occur predominantly along certain planes. A similar scattering pattern is observed on quartz powders: a rectilinear dependence and fractal dimension D=2 are obtained. It is assumed that this peculiarity of X-ray scattering is not related to the property of mineral cleavage.
