Friday, December 5, 2014

Q is for Quartz

Map showing the distribution of sites with quartz artifacts by watershed

Silicate minerals make up approximately 90% of the debris in the earth’s 40 plus kilometer thick mantle which includes granite, basalt, schist and sandstone. In fact, the mineral quartz is one of the most prolific lithic materials then available to prehistoric people for making stone tools. For this discussion, the range of quartz, based largely on diaphanous differences, include crystal, semi-translucent and opaque or milky, depending on the visual clarity of the specimen. The chemical composition of quartz (SiO2) is found in other stone tool materials such as jasper, chert, quartzite and chalcedony.  Taken collectively, quartz and its constituent products was a principal material used to make projectile points and other cutting tools prior to the advent and development of metallurgy. The delicate conchoidal fracture pattern on some artifacts made from milky quartz can be difficult to trace -  ask any lithic analyst who has worked with the stuff.

Some of the typicalt forms of quartz used by different prehistoric cultures

Here in Pennsylvania, quartz was collected prehistorically from stream bottoms, floodplains, hillsides and other locations; wherever erosion managed to release the material from its bedrock source. Some sites were massive workshops. On such sites the land surface is littered with broken cobbles, cores and the telltale flaked debris from humans reducing quartz material to manageable size for transport elsewhere. Other sites consist only of a thin scatter of flakes and perhaps, one or two projectile points suggesting only a brief visit to the spot to hunt, re-sharpen tools or just as a place for the traveler to rest before moving on to the next camp.

Quartz was used throughout the prehistoric cultural continuum, however, the lithic material was seemingly more popular during the Late Archaic, Middle and Late Woodland periods which may have been based on availability rather than cultural preference for quartz as weapons grade material. It is also likely that quartz was the preferred lithic type used for tool production when knapping points for certain tasks such as skinning and butchering animals because of its structurally close grained hardness where, in fact, other lithic materials might have failed.

The following photos of projectile points and other quartz tool forms from the State Museum and private collections are provided for the reader’s benefit. These artifacts are from surface collected sites in the Susquehanna and Delaware drainages of southeastern Pennsylvania.

Paleoindian fluted points. Crystal quartz and opaque milky quartz

Middle Archaic bifurcate points. Semi-translucent and opaque milky quartz

Late Archaic notched and stemmed points of opaque milky quartz

Early –Middle Woodland corner notched, basal notched and teardrop-shaped points of quartz

Late Woodland Levanna and Madison triangular points of opaque milky and semi-translucent quartz

Early stage preforms, side notched scraper and spherically battered hammerstone of opaque milky quartz

Hafted biface of opaque milky quartz showing heavy abrasion from repeated ground impact after 50 atlatl launchings

We hope that you have enjoyed this brief presentation on the use of quartz and the many different stone tool forms fashioned from it. Please consult the For Additional Reading Section at the end of the blog for more information about quartz artifacts and how they were used throughout prehistory. Join us once again next time for another fascinating topic on Pennsylvania archaeology.
                                                              “Save the Past for the Future”.  

For additional reading:

Shultz, Charles H., editor
1999       The Geology of Pennsylvania. Special Publication 1. Pennsylvania Geological Survey and the Pittsburgh Geological Society.  
Custer, Jay F.
2001       Classification Guide for Arrowheads and Spearpoints of Eastern Pennsylvania and the Central Middle Atlantic Projectile Points of Pennsylvania. Pennsylvania Historical and Museum Commission.
Kent, Barry C.
1996       Piney Island and the Archaic of Southeastern Pennsylvania. Pennsylvania Archaeologist 66(2):1-42.

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

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