... Optical properties of oxide dust grains. ... Optical constants: . ... The deternimation of the optical constants was made from measured reflectance at near normal incidence of the polished sample surfaces (0.2 - 500 micron) with following Lorentz oscillator fit (typically 5 oscilators) from ultraviolet to mid-infrared and Kramers-Kronig analysis in the region of the infrared vibrational bands. The oxides Fe x Mg 1-x O for x = 1.0, 0.9, 0.8, 0.7, 0.5, and 0.4 were considered in the paper. ...