A six-flux Monte Carlo approach to modeling of the reflectance of particulate surfaces is presented that includes the scattering as well as absorption of asperities of the constituents. For spherical particles greater, similar lambda, the forward, backward, and transverse scattering is calculated. Then using a radiative transfer model, the reflection of a particulate surface may be determined. An application of the theory is made to four particle size ranges of a nonhomogeneous, multiconstituent sample-the Bruderheim meteorite-of olivine-hypersthene chondritic composition. The theoretical values of reflectance, using the experimentally determined optical complex indices of refraction, compare well with the experimental reflectance observations.