Ashes from pottery and lime kilns, bonfires, cooling fires, ovens, etc. are being characterized using atomic absorption, x-ray diffraction, and scanning electron microscopy to provide a framework within which to interpret archaeological materials. Two groups of ashes have been observed: 1) high temperature types containing calcium carbonate as aragonite, also with fine glassy spherules and silicate phases such as gehlenite and diopside; 2) with calcium carbonate as calcite, no evidence for calcium silicates, and no glassy spherules. Temperature range for 1) is thought to be 850°C-1050°C, and for 2) less than 800°C.