oxides
Chrysoprase
SiO2
- Also known as
- Australian jadeprase
- Crystal system
- trigonal
- Hardness
- 6.5–7 on the Mohs scale
- Lustre
- waxy
- Colour
- Apple green to deep green
- Where it forms
- In the weathered crust above nickel-bearing serpentinite, where nickel released by weathering is taken up into silica gel as it sets.
- Chiefly from
- Marlborough, Queensland, AustraliaSzklary, PolandTanzania
Why it is that colour
Nickel, in the form of finely dispersed hydrated nickel silicates. It is the only common green chalcedony coloured this way, and the colour can fade with heat or prolonged sunlight.
Safety
No hazard from handling. Nickel is present in trace amounts bound in the structure, not in a form that is released by contact.
Where it comes from
The Marlborough deposit in Queensland is the world's principal source and the material is often sold as "Australian jade", which it is not. Historic Silesian production from Szklary is largely worked out.
Historical use
Widely used in Roman jewellery, then in medieval European work, then extensively in the Prussian court after the Silesian deposits were exploited in the eighteenth century. Panels of it survive in the Chapel of St Wenceslas in Prague.
Recorded as history and attributed where possible. That a stone was used for something establishes that people used it, not that it worked.
What is attributed to it, and since when
Named in Greek from chrysos, gold, and prason, leek. It appears in the list of foundation stones in Revelation and was used in Roman and later European jewellery. Frederick the Great of Prussia was particularly fond of Silesian material. Modern meanings attached to it are of recent invention.
Described, not endorsed. Dating a claim is not the same as assessing it — but an association that first appears in a book published in 1985 is not an ancient inheritance, whatever the label says. A sincere account of feeling better is compatible with the stone doing nothing — see the placebo effect.
Sold as this, but not
Worth knowing
Chrysoprase is one of the very few gem materials coloured by nickel, and its colour is a direct signal of the ground it formed in — you find it above weathered ultramafic rock, which is where nickel is. Prospectors have used it as an indicator mineral for exactly that reason.
Its persistent sale as "Australian jade" is the standard shape of the naming problem: a real material, accurately described by its own name, marketed under the name of a more valuable one.
Identity checked against IMA-CNMNC master list, June 2025.