Remote sensing from 700 km, the nominal height for broad coverage, earth observation satellites, has advanced over the decades such that now, with adequate atmospheric correction, the instrument acquired radiance can be converted to spectral reflectance with sufficient accuracy for many applications. Industrial applications require quantitative analyses of material properties and abundances that far exceed those so far obtainable from orbital sensors using the sun as a source, viewing through a changing atmosphere. Although the physics of reflectance spectroscopy is the same for measurements from orbit and over the conveyor belt, the needs for illumination, sample presentation and signal-to-noise ratio drive different approaches for close-up remote sensing. This paper will attempt to illuminate the accuracy, illumination, calibration and stability requirements as well as solutions for systems used to make quantitative, real-time measurements of the properties of rocks on conveyors in industrial applications. Quantitative reflectance spectroscopy has the promise of making a step change in the efficiency of materials processing in factory settings.