Tripoli (Cottonrock, Rottenrock) stone tools
Damaged (broken in prehistory so fully patinated) full grooved axe manufactured out of Tripoli found at a surface site in Shannon County, MO.
Length = 124.11 mm, Width = 73.38 mm, Thickness = 56.00 mm, and Weight = 240 grams.
pXRF 155 and 158
pXRF 153: Barium = 104.3 ppm +/- 37.52, Zirconium = 1409 ppm +/- 6.47, Strontium = 11.63 ppm +/- 2.19, Rubidium = 10.62 ppm +/- 1.68, Arsenic = 6.16 ppm +/- 3.63, Zinc = 38.28 ppm +/- 6.32, Copper = 26.17 ppm +/- 10.07, Iron = 5898.98 ppm +/- 111.63, Manganese = 1068.39 +/- 61.84, and Titanium 1380.04 +/- 716.54
pXRF 160: Zinc = 0.006% +/- 0.001, Iron = 1.209 +/- 0.026, Manganese = 0.046 +/- 0.007, Aluminum/Silica = 98.663% +/- 0.02.
Damaged (modern plow scar) full grooved axe manufactured out of Tripoli found at a surface site in Shannon County, MO.
Length = 142.17 mm, Width = 79.10 mm, Thickness = 33.64 mm, and Weight = 282 grams.
pXRF 156 and 157
Full grooved axe manufactured out of Tripoli found at a surface site in Shannon County, MO.
Length = 124.06 mm, Width = 70.97 mm, Thickness = 45.09 mm, and Weight = 239 grams.
pXRF 154 and 159
Tripoli is a very soft stone that was used to create full grooved axes and adzes that are occasionally found at archaeological sites in Missouri. A modern source of this stone is in Seneca, Missouri. The source and age of the artifacts manufactured out of Tripoli in Missouri is of ongoing interest. Jack Ray at Missouri State University notes that "there are two separate (distinct) types of soft raw material from which ground-stone axes were made. The first, and by far the most common, is cottonrock. Cottonrock is a common name for a particular silty dolostone that occurs throughout the Salem Plateau in the Ordovician-age Jefferson City-Cotter Formation. Tripoli is a desilicified chert that occurs in the Mississippian-age Warsaw Formation on the west side of the Springfield Plateau. Although I have seen 2 or 3 axes made out of this material in the Joplin area, it is relatively uncommon." (Personal communication September 2023).
My interest in this rare material also relates to the suggestion that it was used to create a prehistoric white pigment that contained very small traces of Palladium. pXRF analysis did not detect Palladium in the four specimens (in a private collection) that I studied.
-------------------------------------------------------------------------------------------------------------------
Full grooved axe manufactured out of Tripoli found at a surface site in Shannon County, MO.
Length = 91.51 mm, Width = 67.40 mm, Thickness = 40.92 mm, and Weight = 153.6 grams