Slate backs of iron-pyrite mirrors have been found in the southwestern United States, Mexico, Guatemala, Costa Rica, Panama, Ecuador, and Peru. Three engraved slate disks were recently excavated at two sites in Costa Rica, one at La Fortuna and two at Guacimo. Slate disks in this region are not unusual. Many have traces of the gum that was used for glue, and at least one fragment bears traces of the wooden frame. The significance of these three plaques lies in the designs they bear. These designs indicate that the disks were made between A.D. 435 and 500 in an area remote from lower Central America. Grave objects associated with the mirror backs include reworked jades; gold objects in Cocle, Quimbaya and Guayas styles; and Incised Zoned Bichrome and Negative Painted Incised wares. These disks and the objects associated with them provide insight into pre-Columbian interchange and trade routes in lower Central America, and they suggest that slate disks were important in commerce and perhaps served as ceremonial objects.