Natural Science in Archaeology

84 4 Lithic Materials
4.3.3 Felsite
A general term for any fine-grained, light-colored igneous rock composed chiefly
of quartz and feldspar; felsite can be very hard and cohesive and breaks with a
conchoidal fracture making it valuable as a lithic tool raw material. Hermes and
Ritchie (1997) developed a nondestructive method of using energy-dispersive
X-Ray fluorescence spectroscopy to determine the trace-element concentrations in
archaeological felsites as a guide to provenance.
4.3.4 Rhyolite/Andesite
Rhyolite is nearly the same as felsite but is specifically the volcanic finegrained
mineralogical equivalent of granite. Gramly (1984) reported a rhyolite source in
northern New England (USA) that was exploited for stone tools at a slow rate for
more than 7000 years. Stewart (1984) detailed the prolonged and widespread use
by prehistoric groups of a rhyolite from a small geographic area in the Blue Ridge
province of Maryland and Pennsylvania, USA.
In western Japan, sanukite, a variety of andesite, was exploited from four districts
to manufacture a variety of implements (Warashina et al. 1978). Sanukite and obsidian
were imported from some distance and found at sites ranging in age from Paleolithic
to the Jomon Period of Japan, as reported by Togashi and Matsumoto (1991).
4.3.5 Siliceous Shale/Slate/Schist
As with quartzite, this material fractures conchoidally. Because it is composed
chiefly of silica, it has a hardness approaching 7. It was widely used in North
America, especially in northern Minnesota, for projectile points and other sharp
tools (Harrison et al. 1995).
Slate was a common material in some regions for ceremonial picks crafted by
grinding and polishing. A center for pick production was Ohio, but picks occur
throughout northeastern USA and north into Ontario, Canada (Converse 1978).
Halsey (1984) has argued that these objects functioned as blades of tomahawks. In
eastern Canada, slate was crafted by grinding into bayonets. Some were decorated
and reached lengths of more than 30 cm (Sanger 1973). Slate has been used for
projectile points and ground stone tools during the Neolithic Period in Norway and
Sweden. The earliest evidence for the use of ground slate cutting and thrusting tools
in Scandinavia appears about 6000 BCE (Fitzhugh 1974).
At the Magdalanean site of Gönnersdorf (ca. 13,000 BP), the occupants apparently
spent considerable time making engraved plaques from schist beds located
about 500 m away. Over 500 of these schist plaques have been recovered from the
site (Phillips 1980).