New England Argillites

[gregszybala]

Argillite ( New England )
Argillite is typically coal black when fresh, and it patinates to a dull blackish/gray color, grey, greenish-grey, and bluish-grey. and is commonly pitted.
Argillite from Rhode Island and Ma.,is more platy, more slate in nature, with a fine grain, unlike argillite from Pa. and the much grainier argillite from New Jersey,
Argillite/Argillites are fine grained sedimentary rocks (like mudstone and slate) that have been metamorphosed to varying degrees. As a result, these stones are harder than their original sedimentary rock and thus suitable for limited stone knapping to produce tools. Unfortunately,argillites still maintain a degree of sedimentary platyness and have a tendency to flake in layers,making them somewhat difficult to work. Types of argillite include Black (originating in the Delaware River Valley of New Jersey and Pennsylvania), Maroon (originating from the Chicopee shales in western Massachusetts), Blue-Grey, Tan, Grey (all originating from either the Cambridge slates in the Boston basin or Barrington, Rhode Island), Green Platy (originating in Barrington, Rhode Island and also occurring in glacial drift deposits in the Taunton River Basin),Banded (originating in the Cambridge slates in the Boston basin) and Coarse grained green(Originating in Hull, Massachusetts). Argillites are common in glacial drift deposits in many locals in eastern Massachusetts and occur predominantly in the Late Archaic, although they were also used to a lesser degree in other time periods.

Slaty, sometimes more of a siltstone, most would agree it is quite a poor choice for use in flaked stone tools. It usually works poorly, and the results are often crude. Throw in water weathering on a shore, and you get the picture.



Here are more examples of New England argillite:

And, just a few more very average argillite points from RI.:


photos courtesy of CMD



photos courtesy of pkfrey


usually argillite is worn, and here in S. Jersey looks likes this, though I think these below are from a variety of sources.

photos courtesy of kayakaddict