Henry's Knob, a 1,120-foot mountain near Clover in northern South Carolina, took its name from the Henry family, early settlers who acquired land there before the area shifted from North Carolina to South Carolina in 1772. In the 20th century, the mountain became significant for a kyanite deposit then described as the world's largest. Open-pit mining from 1947 to 1970, including operations by Commercial Ores, removed about 100 feet from the mountain and permanently reshaped the landscape. Long after mining ended, contamination from acid mine drainage and related pollution led to federal investigation, with groundwater impacts affecting about 450 nearby households that depend on well water.