Chrysoprase
Chrysoprase is an apple-green to yellowish-green variety of chalcedony, a cryptocrystalline form of quartz, colored by trace nickel locked into its silica structure. It forms in weathered nickel-rich ultramafic rocks, where silica-bearing groundwater deposits it in cavities and fractures. Fine material is prized in jewelry as one of the few naturally green gemstones that owes its hue to neither chromium nor copper.
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Chrysoprase properties at a glance
| Type | Minerals |
|---|---|
| Chemical formula | SiO2 |
| Mohs hardness | 6.5–7 |
| Crystal system | Trigonal (cryptocrystalline) |
| Luster | Waxy to vitreous |
| Streak | White |
| Cleavage | None |
| Fracture | Conchoidal |
| Specific gravity | 2.58–2.64 |
| Transparency | Translucent |
| Common colors | Apple-green, Green (sometimes with darker spots) |
| Rarity | common |
Geology & background
Chrysoprase develops in the oxidized, weathered zones above nickel laterite deposits, where silica-rich groundwater dissolves nickel from decomposing ultramafic rock and later precipitates it as chalcedony in veins, nodules, and cavity fillings. The finest material historically came from Szklary in Poland and from deposits in Queensland and Western Australia, with additional sources in Brazil, Tanzania, and the United States. Because its color depends on nickel staying locked in the silica structure, chrysoprase can fade if exposed to prolonged heat or strong sunlight over time.
Collectors and lapidaries value chrysoprase for cabochons, beads, and carvings, and it saw historical use in decorative arts, including inlay commissioned by Frederick the Great in Prussia. Buyers should watch for dyed green chalcedony sold under the chrysoprase name, since true nickel-colored material commands a higher price and tends to hold its color better over time. Like other chalcedonies, its toughness makes it durable for everyday jewelry despite only moderate hardness.
How to identify Chrysoprase
Chrysoprase shows an apple-green to grayish-green color with a waxy to dull luster and a white streak, typical of chalcedony generally. It has a hardness of about 6.5 to 7, no cleavage, and a conchoidal fracture, occurring as massive, botryoidal, or nodular material rather than distinct crystals. A gentle heat test can reveal dye in imitation material, since natural chrysoprase color does not concentrate near surface cracks. It is often confused with dyed green chalcedony, prase, or green-dyed jasper.
- Compare the specimen's color, luster, crystal habit, grain size, streak, and locality before confirming.
- Use multiple photos when possible, including a fresh surface and a close view of texture.
Where Chrysoprase is found
Reported from multiple localities worldwide; verify locality against specimen provenance when available.
How much is Chrysoprase worth?
| Entry-level specimen | $2 |
|---|---|
| Typical collector specimen | $20 |
| Premium specimen | $150+ |
Value depends on size, crystal quality, color, locality, rarity, damage, and provenance.
Common uses
- Collector specimens
- Education
- Field identification
- Industrial or lapidary use when suitable
Interesting facts
- Chrysoprase gets its green color from nickel, making it one of the few gem-quality quartz varieties colored by that element rather than chromium or iron.
- Prolonged heat or sunlight can slowly fade chrysoprase's color because the nickel-bearing pigment is somewhat unstable over time.
- Frederick the Great of Prussia was so fond of chrysoprase that he had it used to decorate rooms in his Sanssouci palace.
Care & safety
Handle as a collector specimen until hardness, cleavage, and fracture are verified.
Avoid inhaling dust. Do not cut, grind, or polish unknown specimens without eye protection and a proper respirator.
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