The geological study of rocks is oriented toward examining the nature of the rock by means of chemical analyses and by examination with the petrographic microscope. The problem of the archaeologist is one of identification for which the stereoscopic or binocular microscope is best suited. About 20 criteria have been used in identifying with a binocular microscope flints from archaeological sites in Oklahoma as part of a program to trace the sources for the several kinds of flint used in tool making.