The ancient grinding stones used by Native Americans, called mano and metate, are predecessors to the current-day mortar and pestle used in cooking. American Indians created grinding tools from stone, animal bone, tortoise shells, grass baskets and carved wood. There are two types of grinding stones: conical stone pestles and oval stone grinders. Food items like corn, nuts, maize and berries were ground with these stone tools. Grinding stones had other uses, such as grinding ore mixed with animal fat to create paint.
Oval Stone Pestles with Flat Stone Mortars
Created out of sand or limestone, these types of grinding stones were used to grind nuts and berries. Many such stone artefacts date to the early 1800s. By pushing the smaller oval stone forwards and backwards against a larger flat stone, the food items were ground into a fine powder. Eventually the larger stone would develop a groove lessening the spillage of ground grains and corn.
Basket Mortars and Stone Pestles
Multipurpose baskets created out of willow or grass were used in harvesting as well as grinding. Long, flat baskets with curved sides were used as mortars with oval or conical stone pestles. Conical pestles were generally made of softer soapstone, which made chiselling and carving easier. The grinding stone pestle was pushed back and forth against the basket, thus grinding or pulverising the food item.
Conical Pestles with Concave Stone Bowls
A chiselled, 14-inch conical sandstone pestle used with a concave soapstone bowl or cup is a close forerunner to the culinary pestle and mortar used today. The grinding technique is also similar; one end of the conical pestle is placed in the bowl, an up-and-down pounding motion was used to crush large pieces and then a rotating movement along the sides of the mortar would grind smaller seeds, grains and spices. Positioned like a rolling pin, conical pestles were also rolled inside long concave stones and baskets to grind grains.
Three Grinding Stones Process
In many Native American tribes, such as the Pueblos of New Mexico, a series of three grinding stones were used for grains and corn. The first was a very coarse stone with a cylindrical grinder. Once the grain was ground, the coarse meal was placed on the second, medium-coarse stone where a second grinding produced a finer meal. Finally, the meal is placed on the smoothest grinding stone and reground for a third time; the meal is reduced to a fine powder that is excellent for baking.