Nephrite jade pebbles in transmitted LED light
Nephrite jade is a silicate of magnesium and calcium, with a varying amount of iron ions substituted in place of the magnesium ions. Pure nephrite with no iron content is white, and called mutton-fat jade by the Chinese. The greeny-grey colour indicates substitution with Fe 2+ ions, while yellowy-green indicates the presence of Fe 3+ ions.
It is a product of metamorphism, under conditions of very high pressure but not particularly high temperatures. Pure nephrite is chemically closely related to both talc and asbestos. Like asbestos it consists of long needle-like crystals, but in nephrite they are densely interlocked so it is a particularly tough mineral. This is why it can be carved into delicate curlicues without breaking.
Because of its exceptional toughness it is frequently recovered as river pebbles, the softer minerals that it is often formed in association with (serpentinite, talc, and magnesium marble) having been eroded away.
Nephrite jade pebbles in transmitted LED light
Nephrite jade is a silicate of magnesium and calcium, with a varying amount of iron ions substituted in place of the magnesium ions. Pure nephrite with no iron content is white, and called mutton-fat jade by the Chinese. The greeny-grey colour indicates substitution with Fe 2+ ions, while yellowy-green indicates the presence of Fe 3+ ions.
It is a product of metamorphism, under conditions of very high pressure but not particularly high temperatures. Pure nephrite is chemically closely related to both talc and asbestos. Like asbestos it consists of long needle-like crystals, but in nephrite they are densely interlocked so it is a particularly tough mineral. This is why it can be carved into delicate curlicues without breaking.
Because of its exceptional toughness it is frequently recovered as river pebbles, the softer minerals that it is often formed in association with (serpentinite, talc, and magnesium marble) having been eroded away.