These beehive-shaped kilns were built in the mid-1870's to produce charcoal for the silver mills of Pioche and Bullionville, Nevada. Skilled stone masons quarried rhyolitic tuff from nearby outcrops, carefully dressed the blocks, and joined them with mud and lime mortar. A third kiln originally stood west of the two remaining structures. The Panaca Summit kilns were used until the late 1890's, when the mills at Bullionville closed. Because local silver ore processing required large quantities of fuel, and charcoal burned twice as hot as cordwood while being more economical to transport, it became the preferred fuel for smelting. Swiss and Italian woodcutters known as Carbonari had perfected the charcoal-making process in Europe and brought those skills to Nevada's mining regions in the mid-19th century. Billets, or five foot lengths of wood, were cut from the trunks and branches of pinon pine, juniper, or mountain mahoghany, hauled to the kiln site, and stacked in two vertical tiers within the ovens. Dry grasses and kindling were stuffed into the central chimney of the wood stack and ignited with live coals. Openings around the base of the kiln regulated airflow to create a steady fire, while the vent at the top was plugged to slow and control the burning rate. The Carbonari carefully oversaw combustion of the stack, which required up to 30 days to complete. The charcoal was then allowed to cool for a week before the kiln was carefully opened on a calm day, since spontaneous fires during opening could quickly destroy the contents. Each kiln held over 50 cords and produced an average of 30 bushels of charcoal per cord, enough to smelt one ton of silver ore. The Carbonari received very modest payments for their labor, while most profits were taken by the teamsters and middlemen who delivered the charcoal to the mills.