Surfaces and cross sections of individual quartz sand grains have been examined and compared in the cathodoluminiscence (CL) mode with the scanning electron microscope. Six kinds of nontopographic CL have been found; the presence of non-CL areas commonly is due to the occurrence of a disrupted lattice layer wherever grinding has taken place. This layer is shown to be irregularly distributed, both in cross sections and on grain surfaces; its distribution, depth, and intensity can be examined in detail for the first time. Reversal of CL contrast has been accomplished experimentally by raising the temperature of grains above the alpha-beta transition in quartz (573°C); a similar reversal, found in certain natural sedimentary grains, suggests that they likewise have been heated above the transition temperature. Fractures present on natural grain surfaces in the CL mode can be observed in omissive-mode photographs and probably could be used for environmental interpretation. Detail of the same kind, observed in the CL mode but not in the emissive mode on other grains, could further extend the use of sand-grain surface textures for environmental interpretation.

End_of_Article - Last_Page 789------------