Ten samples of cast iron from Catoctin (active from ca 1776 to 1908) were studied by metallography, scanning electron microscopy, and PIXE analysis on sections, plus carbon analysis. The elemental analyses are tabulated, and the metallography illustrated and discussed. The results imply the use of a charcoal blast furnace using a cold blast (two results might have been the product of a hot blast), a phosphorus-rich ore, casting directly from the furnace, a pouring temperature only slightly above the liquidus point, and a moderate cooling rate suggesting the use of sand molds. One sample of white pig iron was an anomaly that was well suited neither to refining nor founding. The conclusions confirm some historical points adduced regarding the site. See also AATA 20-1067. -- AATA