Mammoth Cave became famous initially because of the large deposits of nitre containing earth within the cave. Massive quantities of saltpeter was manufactured from the cave soils in the early 1800’s through about 1815. The biggest production was during the War of 1812 when the British cut off supplies of gunpowder from the United States. Saltpeter is one of the three main components in gunpowder – the other ingredients are sulfur and charcoal.
There have been many article about saltpeter mining during this time period detailing the process and the tools used. The process is summarized excellently by Horace Hovey in 1891.
1891. Hovey, Horace C. 1891. Guide Book to the Mammoth Cave of Kentucky, Historical, Scientific, and Descriptive, Thirteenth Edition, Revised and Enlarged. Published: (Cincinnati) Robert Clarke & Company, 100 pp. http://archive.org/details/guidebooktomammo02hove
Here is a selection of other articles dealing with Mammoth cave specifically:
1955. Faust, Burton. 1955. Saltpeter Mining Tools Used in Caves. Bulleting of the National Speleological Society, Vol. 17, December 1955, pp. 8-18. http://www.karstportal.org/FileStorage/NSS_news/1955-v017-001.pdf
1967. Faust, Burton. 1967. The History of Saltpeter Mining in Mammoth Cave, Kentucky. Filson Club History Quarterly, Vol. 41, 1967, pp. 5-20. http://filsonhistorical.org/wp-content/uploads/2013/03/41-1-2_The-History-of-Saltpeter-Mining-in-Mammoth-Cave-Kentucky_Faust-Burton.pdf [Part 1].
1967. Faust, Burton. 1967. The History of Saltpeter Mining in Mammoth Cave, Kentucky. Filson Club History Quarterly, Vol. 41, 1967, pp. 127-140. http://filsonhistorical.org/wp-content/uploads/2013/03/41-2-3_The-History-of-Saltpeter-Mining-in-Mammoth-Cave-Kentucky-Parts-II-and-III_Faust-Burton.pdf [Parts 2 &3]
1967. Faust, Burton. 1967. The History of Saltpeter Mining in Mammoth Cave, Kentucky. Filson Club History Quarterly, Vol. 41, 1967, pp. 127-140. http://filsonhistorical.org/wp-content/uploads/2013/03/41-3-4_The-History-of-Saltpeter-Mining-in-Mammoth-Cave-Kentucky_Faust-Burton.pdf [Part 4].
1967. Faust, Burton. 1967. The History of Saltpeter Mining in Mammoth Cave, Kentucky. Filson Club History Quarterly, Vol. 41, 1967, pp. 323-352. http://filsonhistorical.org/wp-content/uploads/2013/03/41-4-4_The-History-of-Saltpetre-Mining-in-Mannoth-Cave-Kentucky-Parts-V-VI-VII_Burton-Faust.pdf [Parts 5, 6, & 7]
1986. Mullin, Marsha A. 1986. Mammoth Cave Saltpeter Works Recording Project, Historic American Engineering Record, HAER No. KY-18. 38 pp. http://lcweb2.loc.gov/pnp/habshaer/ky/ky0200/ky0272/data/ky0272data.pdf
1986. George, Angelo I. 1986. Central Kentucky Gunpowder Factories. Journal of Spelean History, Vol. 20, No. 2, pp. 28-34. http://www.caves.org/section/asha/issues/064.pdf
1986. George, Angelo I. 1986. Central Kentucky Gunpowder Factories. Murray State Archaeology Laboratory, Symposium Proceedings Volume 4, pp. 86-95.(V3_p86-95) http://infosys.murraystate.edu/KWesler/Symposium%20Proceedings%20Volume%204/V3_p086-095.pdf
1986. George, Angelo I. 1986. Saltpeter and Gunpowder Manufacturing in Kentucky. The Filson Club History Quarterly, Vol. 60, No. 2, April 1986, pp. 189-217. http://filsonhistorical.org/wp-content/uploads/2013/03/60-2-2_Saltpeter-and-Gunpowder-Manufacturing-in-Kentucky_George-Angelo-I..pdf
1992. George, Angelo I. and O’Dell, Gary I. 1992. The saltpeter works at Mammoth Cave and the New Madrid Earthquake. The Filson Club History Quarterly, Vol. 66, No. 1, January 1992. http://www.rkci.org/library/mammoth_cave_earthquake.pdf
1997. Duncan, M. Susan. 1997. Examining Early Nineteenth Century Saltpeter Caves: An Archaeological Perspective. Journal of Cave and Karst Studies 59(2): 91-94, August 1997. http://www.caves.org/pub/journal/PDF/V59/V59N2-Duncan.pdf
2013. Crothers, George M., Pappas, Christina A., and Mittendorf, Christian D. 2013. The History and Conservation of Saltpeter Works in Mammoth Cave, Kentucky. in Mammoth Cave National Park’s 10th Research Symposium: February 14 – 15, 2013 Proceedings Celebrating the Diversity of Research in the Mammoth Cave Region. http://brimsbg.org/wp-content/uploads/2013/02/Symposium-Proceedings.pdf