Flint Run jasper, Warren County, Virginia.
Samples obtained along Flint Run in Warren County, Virginia.
Flint Run jasper refers to the cryptocrystalline, microscrystaline, or amorphous form of quartz, given its bright color by iron and other mineral inclusions. It occurs along the western flank of the Blue Ridge Mountains. Colors range from brown to yellow, but reds, greens, blues and grays do occur as streaks or small masses within the matrix. The jasper occurs in a zone of contact between Beekmantown carbonates to the west and the Blue Ridge formations to the east, in an area of overthrust faulting. Chemical weathering of the metavolcanics of the Blue Ridge resulted in a breakdown of their minerals into byproducts such as iron oxide and silica. Dissolved silica in groundwater was precipitated as jasper in certain of the carbonate zones. There are two overthrust faults in the region, one runs to the east of Bentonville and Front Royal, and the other runs just southeast of Luray, Virginia. The presence of several optimum geological conditions for the formation of jasper have been noted in this region: 1) Metavolcanics, rich in silica; 2) carbonates, in which the silica could precipitate; 3) the overthrust fault, which brought two different rock types in contact with one another; and 4) a zone of easy access such as fractures, through which the groundwater could travel from the metavolcanics to the carbonates.
Artifacts from this jasper are distributed throughout the northern Shenandoah Valley, particular on its eastern side along the South Fork of the Shenandoah River.
Flint Run jasper was used by Native Americans from Paleoindian through the Late Woodland periods.
Prepared By Walker 1999
Updated: October 22, 2016