Archae Solenhofen (firstname.lastname@example.org)
(Last modified April 17, 2001)
Jade is a metamorphic rock, which forms under medium to high-grade metamorphic facies during episodes of regional metamorphism of mafic and ultramafic rocks, consisting almost entirely of either the minerals nephrite (Ca2(Fe, Mg)5Si8O22·(OH, F)2) or jadeite (NaAlSi2O6). Both of these metamorphic minerals can be coloured white, grey, or various shades of green, and both are translucent exhibiting a somewhat waxy to greasy lustre. The hardness of nephrite and jadeite are 6.0-6.5 and 6.5-7.0 on Mohs' scale, respectively. The nature of the intergrowth of the mineral grains in jade make it a rock of high rock hardness, especially in the case of nephrite, which also has a very high fracture toughness. The rock jade is not native to Egypt.
Several ancient Egyptian artifacts of what is thought to be jade have been found in Egypt. These include such things as axe-heads, scarabs, an ointment pot, and a ring. It has been suggested (Lucas & Harris, 1962) that many of these artifacts may not be made of jade, but other green minerals found in Egypt. For example, non-nephrite tremolite-actinolite group amphiboles, green jasper, or serpentine, all of which can be mistaken for nephrite. Based on a test of specific gravity, a double signet ring found in the tomb of Tutankhamun is thought to be nephrite jade (Lucas & Harris, 1962). Those artifacts that appear to be jade are most likely of the nephrite variety, and the rough stone would likely be imported from Asia.
Lucas, A. & Harris, J.R. (1962) Ancient Egyptian materials
and industries. E. Arnold, London, 523 p.
Links to examples of jade usage
a) Misc objects