Natural Science in Archaeology

Chapter 4
Lithic Materials
4.1 Introduction
Archaeologists use the word lithic (from the Greek lithos meaning stone or rock) for
materials and artifacts made from rocks or minerals. Geologic nomenclature also
makes extensive use of this Greek root, e.g., in lithification (the compaction and
cementation of an unconsolidated sediment into a coherent, solid rock), lithology
(the description of the characteristics of a rock, such as color, mineralogy, and grain
size), and lithosphere (the solid portion of the earth, as contrasted to atmosphere and
hydrosphere). Geologists have used the term lithic to describe volcanic tuffs rich in
fragments of volcanic rocks, as contrasted to tuffs rich in unattached crystals and
glassy particles (shards). Geologists have also used the term lithic to denote sandstones
that contain less than 90–95% quartz plus chert and with more rock fragments
than feldspars. A broad introduction to lithic resource studies, including terminology,
sampling, provenance, geologic and chemical analyses and cultural resource management
aspects, is given in Church (1994). This chapter focuses on lithics as the term is
used by archaeologists, i.e., primarily on materials used for tools or weapons.
The required characteristics for the best chipped stone lithics are hardness, cohesiveness
(lack of brittleness), and perfect conchoidal fracture. Conchoidal fracture
resembles the surface of a shell and derives its name from the Latin concha (Greek
cogche) meaning “mussel.”
Ground stone techniques added another dimension to tool technology. A ground and
polished celt can chop wood better than a flaked axe. Such tools were first shaped by
flaking, then ground by rubbing on a slab of gritty rock such as sandstone and finally
polished by rubbing with a finer-grained rock, using a fine sand as an abrasive.
Humans learned early that some kinds of rocks were far better than others for
chipping into tools. These turned out to be high-silica rocks that broke with a
conchoidal fracture. Hard siliceous materials are not easily weathered away nor
mechanically decomposed during erosion so many prehistoric groups gathered their
chipped stone and ground stone raw materials from river gravels. Local materials
recovered from a creek drainage in Texas included quartzite, chert, petrified wood
and ferruginous sandstone – all tough, high silica rocks. (Furman and Amick 2005)
High-silica rocks not only break conchoidally, but are also extremely resistant to
G. Rapp, Archaeomineralogy, 2nd ed., Natural Science in Archaeology,
DOI 10.1007/978-3-540-78594-1_4, © Springer-Verlag Berlin Heidelberg 2009
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