Journal article about Saltpeter mining, with descriptions, charts, maps, locations, and black-and-white photographs.
Marion O. Smith, "Saltpeter Mining and the Civil War in Jackson County, Alabama," Journal of Spelean History, Vol. 24, No. 2, April-June, 1990 [Maryville: Byron's Graphic Arts, 1990].
Link to Journal [This link is a PDF download; 48 pages].