SALTPETER MINING IN SINNETT CAVE (PENDLETON COUNTY, WEST VIRGINIA) DURING THE AMERICAN CIVIL WAR

Many caves in Pendleton County (West Virginia) contain soil that is rich in nitrate, which was used in making gunpowder before 1870. During the American Civil War, much of Pendleton County remained loyal to the Confederacy, and there are several accounts of Union soldiers attacking Confederate buildings and nitrate leaching vats in the county. Sinnett Cave, which is located near the town of Moyers, was one of the Pendleton County caves where nitrate was mined. The cave has developed on the Long Ridge Anticline, within limestones of the Silurian-Devonian Helderberg Group. Analyses of three soil samples from the cave (collected March 29, 2003) have revealed nitrate concentrations of 478, 482, and 580 ppm. During the Civil War, soil was dug out of a large room in an upper level of the cave (“the Big Room”), and dumped down pits and fissures to the main passage of the cave. The soil was then placed in bags, carried out of the cave, and placed in leaching vats with fresh water. After standing for some time, the cave soil leachate (“mother liquor”) was drained from the leaching vats and into collecting troughs. In a separate container, wood ashes (rich in potassium hydroxide) were leached with water, and this wood ash leachate was combined with the cave soil leachate (rich in nitrate). After additional steps of concentration and purification, crystals of potassium nitrate (“saltpeter” or “saltpetre”) were recovered from the liquid. This potassium nitrate was mixed with charcoal and sulfur to produce gunpowder.