“Jade” gets used as though it names a single stone, a specific shade of green with a specific texture. It actually covers two chemically unrelated minerals, jadeite and nephrite, that happen to share a similar look and an almost identical toughness, and got lumped under one name centuries before mineralogy had the tools to tell them apart.
Two different mineral families entirely
Jadeite is a pyroxene, sodium aluminum silicate, and nephrite is an amphibole, a calcium magnesium iron silicate, two structurally distinct mineral groups that aren’t otherwise easily confused for each other. What they share is a dense mat of microscopic interlocking fibrous crystals, which is the real reason both materials carve and polish so well and resist chipping far better than a single large crystal of comparable hardness would. Our piece on rock, mineral, and crystal terminology touches on this kind of naming mismatch, where tradition and chemistry don’t line up, more broadly.
Toughness, not just hardness
Jadeite and nephrite both sit in the middle of the Mohs scale, roughly 6 to 7, unremarkable next to quartz or corundum. What sets them apart is toughness, resistance to breaking or chipping under impact, which comes from that interlocking fibrous structure rather than from raw hardness. It’s the clearest real-world illustration of why those two properties get measured separately: a large single quartz crystal is harder than jade but shatters far more easily under a sharp blow, because quartz’s strength runs along clean crystallographic directions that a single well-placed strike can exploit, while jade’s tangled fiber structure has no single weak direction to fail along.
That toughness is exactly why jade became the material of choice for tools and ceremonial objects across multiple ancient cultures independently, in China, Mesoamerica, and New Zealand, on opposite sides of the world with no contact between them, arriving at the same material conclusion from the same physical property.
