Natural Science in Archaeology

100 5 Gemstones, Seal Stones, and Ceremonial Stones
and white bands, while the bands of sardonyx are alternating red or reddish-brown
and white. The name takes its origin from Greek onyx, meaning “nail.” Onyx beads
have been associated with Predynastic Egyptian graves. The earliest known use of
sardonyx in ancient Egypt dates from the 19th Dynasty, but it became more common
during the 22nd Dynasty and later (Lucas 1989). According to Pliny, sarda
came from India, Arabia, Persia, Babylon, the Troad, Paros, Egypt, and Epirus
(N.H. 37.80, 90, 91, 105–106, 116, 197). Sardonyx came from India and Arabia
(N.H. 37.4, 85–89, 90, 197). It was used as a gemstone, for seal stones and small
decorative objects. Roman soldiers wore sardonyx engraved with figures of Mars or
Hercules to give them courage.
Prase. The color of this translucent gemstone is green, taking its name from the
Greek word for “leek green.” Although prasius is mentioned by Pliny, he does not
list any source where it might be found (N.H. 37.113). Prase was used for gems and
seal stones.
Hornstone/Chert. This material is found in shades of gray or brown. The name
originated as a mining term. Chert was mined in the Egyptian Eastern Desert, and
occurs in roughly shaped bangles and pendants of the Predynastic and Early Dynastic
Periods (Andrews 1991). In classical antiquity it was made into gems and seal stones.
5.3 Non-Quartz Silicates and Minerals
5.3.1 Coarse-Grained
Olivine (forsterite), Mg 2 SiO 4 , has a hardness of 7 and a density of 3.28. It is found
in basic and ultrabasic rocks. The name olivine derives from its olive green color.
Chrysolite/Peridot: Chrysolite is Greek for “gold frost”; peridot is a French word of
unknown origin. Forsterite was named for Adolarius Jacob Forster (1739–1806), an
English mineral collector and dealer. This mineral was often confused with emerald.
Transparent to translucent, it is found in green, lemon-yellow, and white varieties.
Pliny indicates a major source of peridot was the island of St. John, an Egyptian
island located in the Red Sea. This source (now exhausted) was mentioned by
Al-Biruni in the eleventh century (Sersen 1995). Peridot appeared in ancient Greece
and Rome after Alexander the Great’s conquests (Spier 1989). Pliny’s chrysoberyllus
(a pale-green stone approaching gold) may be a peridot. He does not list its
source. (N.H. 37.76). Pliny also states that topazus comes from St. John’s Island
and the Thebaid (N.H. 37.24, 107–109). Varieties of this stone were highly prized
in antiquity and used as gemstones. It is mentioned in the Biblical book of Revelations
as a precious stone. Large peridot crystals are found in the Mogok district of
Myanmar.
Beryl, Be 3 Al 2 Si 6 O 18 , has a hardness of 7.5–8 and a density that varies from 2
to 2.9. It appears in several varieties. Common beryl is green and often opaque
but may occur in gem forms as emerald (green), aquamarine (blue), or morganite