Pitkin chert

Pitkin chert comes from the Pitkin Limestone (Pitkin Formation), a Late Mississippian unit of the Ozark Plateaus in northern Arkansas and eastern Oklahoma, named for exposures near the Pitkin post office in Washington County, Arkansas. The Arkansas Geological Survey describes the formation as an oolitic, fossil-rich limestone with only minor chert near its top or bottom. Even so, the chert travelled. In Mississippi, Dalton points are occasionally of Pitkin chert from northwest Arkansas, it is one of the distant stones well represented among Scallorn arrow points, and some Nodena points at the Oliver site in Coahoma County are of it. In Missouri, at least one Sedgwick fluted point of exotic Pitkin chert was found near the Current and Jacks Fork rivers.

Pitkin Limestone/Formation, Late Mississippian: usually a fine- to coarse-grained oolitic, bioclastic limestone with black shale interbeds in the east; minor chert sometimes near the top or bottom. Fossils include crinoids, brachiopods, bryozoans (Archimedes is a good marker), corals, cephalopods and shark teeth. A thin edge to over 400 feet thick, averaging about 50 feet in the west and 200 feet in the east (Arkansas Geological Survey).