Jade

Jade is not a mineral. It is a term covering two chemically unrelated minerals that were not distinguished until 1863, when the French mineralogist Alexis Damour separated them.

Nephrite is a calcium magnesium iron silicate of the amphibole group, occurring as a dense felted mass of interlocking fibres. Jadeite is a sodium aluminium silicate of the pyroxene group, granular rather than fibrous, harder, rarer and capable of more intense colour, the emerald-green fei cui or imperial jade is jadeite.

Their shared property, and the reason both were prized, is toughness. Jade is not particularly hard (nephrite is around 6, jadeite around 6.5 to 7, both below quartz), but its interlocking microstructure makes it extraordinarily resistant to fracture. Nephrite is among the toughest natural materials known, tougher than steel by some measures of fracture resistance. This is why jade was worked into axes and weapons in the Neolithic across Europe, Asia and the Pacific: it was the best available material for an edge that would not shatter.

The consequence for craft is that jade cannot be carved in the ordinary sense. It is too tough to cut and it has no cleavage to exploit. It must be abraded, ground away with harder sand and slurry using saws, drills and wheels, which is enormously slow. A major Chinese jade carving represents years of work, and this labour is part of what the material has always signified.

Chinese jade is nephrite until the eighteenth century, when Burmese jadeite began arriving in quantity. Mesoamerican jade is jadeite, from the Motagua valley in Guatemala.

Two civilisations on opposite sides of the world, with no contact, made jade their supreme material. Neither valued gold comparably. This is a genuinely remarkable convergence and it has a partly practical explanation: both had access to jade and neither had a strong tradition of transparent faceted gemstones, and toughness matters more than brilliance when the object is a tool, a seal or a ritual implement.

In China jade is yu, and the word carries a moral weight that has no English equivalent. The Liji, the Book of Rites, records Confucius comparing the qualities of jade to the virtues of the superior man: its warmth to benevolence, its firmness to intelligence, its sound when struck to music. Jade objects structure Chinese ritual from the Neolithic: the bi disc and the cong tube of the Liangzhu culture, before 3000 BC, are among the most labour-intensive objects any Neolithic society produced, and their function is unknown. Jade burial suits sewn with gold wire were made for Han princes on the belief that jade preserved the body; the excavated examples show it did not.

In Mesoamerica the Olmec, Maya and Aztec valued green jadeite above all other materials, associating it with maize, water, breath and life. Jade beads were placed in the mouths of the dead. The Motagua source was lost after the conquest and only rediscovered in the twentieth century.

Modern Western jade lore (luck, harmony, protection), is a thin extract from the Chinese material, transmitted through the export trade. The Vedic tradition does not use jade among the navaratna, and jade has no classical Western planetary attribution at all; assignments found in modern tables are recent.