Argillite (N. Carolina)

[gregszybala]

Composed of alternating layers of clay and silt.The major characteristic of this material is it's graded bedding, usually 15mm or less in thickness, which make it difficult to flake in a predictable fashion. Argillite is a major geological component in the southern Uwharrie Mountains along with greenstone and rhyolite.

Information and photo courtesy of Truett