These Sinagua Indians were artisans who manufactured pottery, and stone and shell ornaments. Their pottery was a reddish-brown ware (so colored from minerals in the native clay) and it was usually undecorated, though sometimes painted red. Sand was used as a tempering or binding agent. They made pottery bowls, cooking pots, and water jars—some of the latter of 3- or 4-gallon capacity. In refuse dumps near the dwellings, archeologists have found quantities of broken pottery—it is principally through a study of these dumps that the chronology of Indian occupation in this area is revealed. Pottery was made from clay found in the region. After the clay was pulverized, the correct amounts of water and tempering materials were added. There were no potter’s wheels, so the vessels were shaped by hand. The Sinagua accomplished this with the aid of a stone “anvil” held inside the pot and a wooden paddle used against the outside. Finishing was usually done by rubbing the surface perfectly smooth with a polishing stone or pebble dipped in water. Although some Indian pottery has a high polish, none of it carries a true, over-all glaze. Modern Indians, in firing their pottery, usually burn animal dung for fuel, but the pre-Columbian Indians used vegetable material, possibly juniper wood. Several pieces of pottery might be stacked together so that all would be evenly exposed to the heat of the fire. Large pieces of broken pottery were used to protect the new pieces from direct contact with the flames. The firing process required several hours, with time allowed for the pottery to cool slowly. Stone and shell ornaments are examples of other crafts, and some beautiful specimens have been found. The shells came from the Pacific Ocean or the Gulf of California and are believed to have been imported through trade with neighboring tribes. Prehistoric trade routes, over which specific types of shells were distributed, extended from the Gulfs of Mexico and California to north-central New Mexico and from the Pacific Ocean to southern Utah. The shell was worked in various ways. The tips were ground from olivella shells which were then strung on sinew and worn as beads. Larger shells were sometimes covered with a mosaic of turquoise and colored stones. The turquoise was mined with stone tools, and by the time it was removed from its matrix, cut, and polished, it represented a considerable investment of labor. Argillite found in the Verde River region was also mined. Lac, an insect secretion found on creosote bushes, was sometimes used to cement the turquoise and argillite to the shell base.