Monolayer Polished Sections (MPS). Sample preparation for quantitative mineralogical investigations of the heavy mineral HS concentrates is usually made in the form of polished mounts of volume grains. Final HS concentrate (FC) of each size fraction is represented by grains of the same size range. Thus, careful polishing of the mount surface provides perfect cross section through the middle of every grain. As a result, such valuable information as real grain size distribution, mineral liberation and associations are easily obtained in very short time using different methods of in-situ mineralogical investigations of MPS.