Natural Science in Archaeology

178 7 Metals and Related Minerals and Ores
In North America, where no smelting occurred in antiquity, the brilliant silvery
luster of galena nevertheless attracted the indigenous peoples, and it was used extensively
in burial practices and for ornaments. Geologic sources of galena are numerous
in the region from the southern Appalachians to the western Great Lakes area
and from Virginia to northeastern Oklahoma. Galena was used by North American
prehistoric peoples for perhaps 8000 years. The large archaeological site at Cahokia,
Illinois, located near a major source, was a significant consumer and exporter (Walthall
1981). The earliest use here was during the Early Archaic. Of the 232 sites reported
by Walthall (1981), 60% were mortuary sites with galena in a burial association.
Galena has been reported from over 200 prehistoric sites in eastern North
America, but is rarely found in sites before Late Archaic. It is found at Late Archaic/
Early Woodland Period(s) in the Great Lakes and Mississippi Valley regions. During
the Middle Woodland, a large quantity of galena was moved through regional
and long-distance exchange systems. Over 60 Mississippian sites, located from
Illinois to the southern Appalachians, contained galena. These artifacts often exhibited
ground facets. Galena has been recovered from archaeological sites throughout
most of North America. It was valued for use in ceremonial objects because of its
attractive silvery color and perfect cubic cleavage. The individual pieces varied
from 30 g to 100 kg and from 5 to 15 cm in diameter (Walthall et al. 1980). At least
one group made a gray paint from finely ground galena.
Galena is available at or near the surface in more than 20 states in the United
States and also across Canada. The earliest significant exploitation in North America
occurred in the second millennium BCE where small pieces were placed in burials with
red ochre. The most extensive use of galena in North America occurred from about
300 BCE to about 400 CE when it was traded over distances greater than 1000 km.
The largest and most accessible deposits were found in the Upper Mississippi Valley
(UMV) region near the border of Illinois, Wisconsin, and Iowa. Early exploitation
of these deposits is well documented (Agnew 1955). Source assignments using
atomic absorption (AA) spectrometry are provided by Walthall (1981) and Walthall
et al. (1979, 1980), and lead isotope analyses by Farquhar and Fletcher (1984). These
authors found that the galena from Archaic/Woodland sites in northeastern North
America had various sources. Galena from five sites probably originated from a single
vein near Rossie, New York. One galena source may have been a vein close to the
Ottawa River, Ontario, and another in the southern part of the UMV region. Walthall
and his associates traced galena to the UMV deposits and elsewhere in the eastern
United States. In the United States, lead ore deposits in the Illinois/Kentucky region
also contained fluorite (CaF 2 ) that was carved into figurines by prehistoric people.
7.10 Zinc (Zn) Minerals
The most common zinc ore is sphalerite (ZnS), also called zincblende or just blende.
It has a hardness of 3.5–4.0 and a density of 3.9–4.1. Zinc carbonate, smithsonite
(ZnCO 3 ), is less common than sphalerite, but it is much easier to smelt than sphalerite