The processing of Paleolithic pigments from three caves in France was studied, based on 26 samples from Arcy-sur-Cure, ca. 35, 000-25,000 B.C.; 43 samples from Lascaux, ca. 14,500 B.C. and 19 samples from Mas d'Azil, ca. 11, 000 B.C. Initially a data base of microstructures and compositions of naturally occurring materials was established as a reference collection. 165 standards were derived from geological sources within a 15 km. radius of each cave, from geological and art museum pigment collections, from old master drawings, and from other French caves and open air sites. The range of composition and microstructure of each cave sample was determined by optical microscopy, scanning electron microscopy with simultaneous energy dispersive x-ray analysis and x-ray diffraction. Wet and dry streak colors, flowability and particle size of accessory minerals were characterized to determine suitability as pigments. Potential raw materials and samples in different stages of processing were studied. Studies aimed to replicate processing steps were analyzed using the same methods as the ancient potential pigments. This study demonstrates that selection, preparation and use of various soft stones in cave drawings at Lascaux is a complex technology involving selection, collection, grinding, mixing during grinding and application, and different methods of application for different colors. This soft stone technology displays individual and cultural patterning in the processing of pigments which differs from site to site.