Natural Science in Archaeology

5.2 Quartz Minerals (SiO 2 ) 95
quartz objects were glazed until about 200 BCE (Singer et al. 1956). According to
the Bible rock crystal was one of the gems used to decorate the foundations of the
city of Jerusalem.
In the Greek play “Clouds” by Aristophanes there is mention of a stone used to
concentrate the sun’s rays enough to start fires. This must have been rock crystal.
The early craftsmen of Rome secured rock crystal from the Swiss Alps and the
island of Madagascar. These deposits produced huge crystals (over 100 kg) suitable
for large carvings. The Chinese also made large carvings and spheres from crystals
originating from a pegmatite in Myanmar.
Rock crystal was also used in North America for projectile points. Natural
quartz crystals were used for ritual purposes by prehistoric peoples in California
beginning about 6500 years BP (Beardsley 1954). A cross fashioned from a single
quartz crystal was uncovered from a seventeenth century Franciscan mission site at
Tallahassee, Florida (McEwan et al. 1997). Although the artifact shape combines
Native American and Christian symbolism, the manufacturing techniques suggest
the cross was fashioned by a Native American artisan.
Amethyst. Amethyst is characterized by various shades of purple or violet. The
cause of color in amethyst is discussed in Cohen (1985, 1989). Its name is derived
from Greek, meaning “not drunk.” Amethyst crystals occur widely in hydrothermal
veins formed at relatively low temperatures and pressures. The principal use
of amethyst was for gem-stones, beads, and seal stones. Unfortunately, the name
“amethyst” has also been applied to corundum and beryl in the literature.
Amethyst was mined in Egypt as early as the First Dynasty (2920–2770 BCE)
(Lucas 1989). Amethyst from this region was also exploited by the Romans and
was worn in ancient Israel by the high priests. Pliny lists amethystus sources
as India, Arabia, Petra, Syria, Lesser Armenia, Egypt, and Cyprus (N.H. 37.91,
121–124, 125). Other varieties that he calls sangenon (N.H. 37.84, 130) and
socondios (N.H. 37.122) also came from India. Sapenos has also been identified
as amethyst, but Pliny does not list its source (N.H. 37.122). Tenites from Egypt
may have also been amethyst (N.H. 37.130). Pliny (N.H. 37.122) also uses the
name pharantis as a type of amethyst. Catherine the Great of Russia was famed
for her amethysts which came from mines in the Ural Mountains. In the “Old
Testament” amethyst is the ninth stone that decorated the high priest’s breastplate;
but it should be noted that various translations of the Bible disagree on
mineral names.
In ancient Europe amethyst and citrine were popular but relatively scarce. In
India deposits were more abundant and have been exploited for thousands of years
but these gemstones were much less popular. Amethyst is not represented in the
Indian legend of the creation of gems. At archaeological sites in India contemporary
with the Roman Empire amethyst is far less common than rock crystal, agate
carnelian and related quartz minerals. The abundance of quartz gems in India stems
from the extraordinary Mesozoic volcanic activity that formed the Deccan Trap.
These basaltic rocks were often vesicular leading to later deposition of minerals
from percolating water. For a review of the early mining and working of amethyst
and citrine in the Indian subcontinent, see Francis (1986).