Natural Science in Archaeology

108 5 Gemstones, Seal Stones, and Ceremonial Stones
off and on since the Neolithic for the manufacture of jewellery and ornaments. This
was an important source for the carvers of Prague in the sixteenth and seventeenth
centuries. Modern exploitation occurs exclusively within the contact alteration zone
along faulted margins between serpentinite and diorite/gabbro rocks. (Nichol 2001).
Early European explorers recorded the use of nephrite by aboriginals in British
Columbia and Alaska. The source was determined to be the Columbia River Basin
and the Kobuk River in Alaska (Desautels 1986).
Using electron microprobe analyses Hung et al. (2007) have mapped the distribution
of nephrite atifacts from deposits on Taiwan, including the Fengtian deposit,
and elsewhere in Southeast Asia. Artifacts dating from 3000 BCE to 1000 CE were
exchanged throughout a large region including the Philippines, Thailand, Malaysia,
and Vietnam. Jade carving developed in India with the advent of the Mughal
emperors, who brought knowledge of the craft from east central Asia and Iran.
Jadeite is a pyroxene with the chemical composition Na(Al,Fe)Si 2 O 6 , a hardness
of 6–7, and a density of 3.25. It is usually light to dark green, but it may also be
dull white. Massive material is pale green to emerald green, greenish-white, gray,
mauve, or white. It may be stained by iron oxides to various shades of brown, red,
orange, or yellow. Its name is derived from Spanish “piedra de yjada” (stone of the
side). Jadeites come in colors ranging from white through pink, lilac, red, brown,
orange, green, blue, to black. The colors are derived primarily from trace elements
incorporated in the mineral structure. For example, in white jadeite all the iron is
ferric while in black jadeite one-half is ferrous. The highest quality green Bumese
jadeite has up to 0.3 per cent chromium (Harder 1995).
The Aztecs, Mayas, and other precontact peoples of Mexico and Central America
carved green jadeite for ornaments and amulets. Only the Montagua Valley of Guatemala
has been established definitively as a source for Precolumbian jadeite in the
New World. There is considerable speculation and research directed at the identification
of other Mesoamerican sources, but none have yet been confirmed. Researchers
have suggested other possible sources in Costa Rica (Soto n.d.) and Mexico
(Fig. 5.5). Olmec knowledge of jadeite extends back to the Early Preclassic Period, in
the second millennium BCE. Jadeite celts, ornaments, and gems have been recovered
from workshop sites on the island of Antiqua, West Indies. These are dated to circa
250–500 CE. (Harlow 2006) Guatemala is a reasonable source for these jades.
In the Old World, Neolithic and Bronze Age jadeite axes have been found in
Italy, France, and other parts of Europe. Evidence suggests that the source of this
material was the western Alps (D’Amico et al. 1995). In China, jadeite artifacts dating
from the eleventh century BCE and later have been found. Sources may have
been in China’s Shanxi and Yunnan provinces, and from Tibet (Whitlock 1934) and
Burma (Desautels 1986). Jadeite has been used in carvings, decorative and ceremonial
objects, personal ornaments, and gems.
Chloromelanite is impure jadeite. It is dark green or blackish in color. Its name
comes from the Greek word for “green-black.” It is commonly found in Mesoamerica
where it was used for gems, carvings, decorative and ceremonial objects,
and personal ornaments. It was also found in the form of tools in Mesoamerica,
New Guinea, and Neolithic sites in Europe (Bishop et al. 1985).