Friday, May 20, 2011

"J" is for. . .

“J” is for jar, Jack’s Reef, Jamestown and this week “J” is for jasper. Pennsylvania jasper has been used to make stone tools for at least 11,000 years and was used by early Native Americans all over the East Coast, from New Brunswick to North Carolina. Jasper can be defined as a yellow, red or brown, cryptocrystalline or microcrystalline chert given its color by iron and other mineral inclusions. It can also be found in black or green. Its geologic origins are debated but it is most likely a sedimentary rock formed by the replacement of carbonates (limestone) by silica (quartz). Several major outcrops are found at the boundary between the silica rocks of Precambrian Blue Ridge province and the Cambrian/Ordovician rocks of the Valley and Ridge province.

There are two major quarry formations in Pennsylvania. The Bald Eagle/Houserville quarries near State College and the Hardyston (Reading Prong) quarries south and west of Allentown. Major sources in adjacent states are the Iron Hill quarries in Delaware along the Pennsylvania line and the Flint Run quarries in the Shenandoah valley of northern Virginia.

Jasper was desirable as a toolstone because it is available in very large blocks (the package size), thus there are no restrictions on the size of artifacts that could be produced; it is available in very large quantities; thus it could be used in trade; and it has a fine (microcrystalline), glass-like structure; allowing for highly controlled (predictable) flaking techniques. The disadvantage is that it sometimes contains voids and impurities which require testing at the quarry to reduce the probability of bringing home a poor quality piece.

The Bald Eagle/Houserville quarries are concentrated in the State College area and the raw material seems to have been collected from the ground surface without much effort. However, much of this source is course in texture and it does not seem to have been used over an area outside of central Pennsylvania.

The Hardyston jasper quarries consist of a series of major outcrops that extend over an area of 25 miles. Henry Chapman Mercer mapped over twenty separate quarries in the 1890s. This formation is arguably the best quality lithic material in the Middle Atlantic region. Large pits were dug to extract it from the decaying bedrock. Mercer reported pits over 50 feet in depth. Excavations by the Pennsylvania Historical and Museum Commission documented depths of up to 24 feet and 80 feet across.

Jasper has been used throughout prehistory. Its widest distribution was during Paleoindian times when Pennsylvania jasper was carried to sites in Maine. It continued to be a preferred material during the Early Archaic period but during the Middle and Late Archaic it witnessed a decrease in use. Its most intensive use was during the Transitional period when it was traded throughout the Middle Atlantic region. It is strongly associated with Lehigh and Perkiomen broadspears and fishtail projectile points. During early Late Woodland times it was the preferred stone for the production of Jack’s Reef projectile points (see above, top center). These are finely made and very thin and may have been the first tips used with the bow and arrow.

Archaeologists trace the movements of prehistoric groups and patterns of trade and exchange by tracing how far lithics have moved from a given source. There are a variety of techniques such as chemical characterization as determined by neutron activation, atomic absorption and flame emission spectrophotometry, or X-ray fluorescence. Very simply stated, these methods determine the precise chemical composition of the different quarries (especially focusing on rare elements) and match artifacts to these chemical compositions. These methods have documented a Middle Archaic artifact found in central New Jersey as having originated in the Flint Run quarries in Virginia and a Paleoindian artifact from Maine originating in the Hardyston quarries. It has taken over 20 years to perfect these methods but they hold promise of making significant contributions to our understanding of past migrations and trading patterns.

For more information, visit or the Hall of Anthropology and Archaeology at The State Museum of Pennsylvania .


Stevenson, C. M., M. D. Glasscock, R. J. Speakman, and M. MacCarthy

2008 Expanding the Geochemical Database for Virginia Jasper Sources. Journal of Middle Atlantic Archaeology 24: 57-78.


  1. Is there an archaeologist at the State Museum that can recognize Pennsylvania jasper from an image sent via e-mail? It's a point called Morrow Moountain II.

  2. Anonymous, thanks for the comment. Send us a photo of the point via e-mail -, or and we will attempt to identify the lithic material.