Chrysoprase: Real Nickel Green, Lemon Magnesite and Dyed Look-Alikes

Short answer: chrysoprase is translucent apple-green chalcedony (SiO2, Mohs 7, SG 2.63 to 2.65) whose color comes from nickel, and most of the good material now comes from the Marlborough district of Queensland, Australia. Two things sold under the same name are not chrysoprase: opaque "lemon chrysoprase", which is magnesite at roughly Mohs 4, and green-dyed grey chalcedony. Real stones show slight color variation and can fade in strong sun or heat.

Why is chrysoprase green?

Nickel, and not as a neat substitution inside the quartz. Geology.com explains that small amounts of nickel silicate admixed with the quartz, dispersed nickel oxide and free nickel ions may all contribute, and that the nickel is not believed to enter the lattice of the microcrystalline quartz itself. That is a useful mental model for a buyer: the green is carried by tiny nickel compounds sitting between the quartz fibers, which is why it behaves differently from the iron that colors carnelian.

The amount of nickel sets the depth of color. Pale yellowish green material can contain between 0.2 and 1.0 weight percent nickel oxide, while deep green specimens can carry up to 5 weight percent. Minerals.net adds a naming boundary at the dark end: once the green passes a certain darkness, the trade stops calling it chrysoprase and calls it prase. In practice the market rewards a saturated, even apple green with good translucency, and a stone that looks like green glass lit from inside is the top of the range.

The numbers

Figures from Minerals.net on chrysoprase. Because it is a variety of chalcedony, it shares the toughness of the whole family: no cleavage, conchoidal fracture and a hardness that resists everyday scratching.

Where does chrysoprase form?

In weathered nickel-bearing rock at shallow depth. Geology.com describes it filling cavities, veins and fractures within or near peridotite, dunite and serpentinite, rocks that are often part of an ophiolite or a subduction zone. As those rocks weather, nickel is released and travels with silica-bearing groundwater into cracks, where the chalcedony grows. The veins are usually under a few inches wide and rarely run more than several feet, which is why the rough comes out in small pieces and chrysoprase is mined by the kilogram and not by the ton. That single fact explains most of its pricing: large, clean, evenly colored slabs simply do not occur often.

The main localities

• Poland (Szklary). The historical European source. Mining at Szklary began in the Middle Ages and continued on and off until 1980, with renewed activity from 2010. Minerals.net notes that Poland was the only source of chrysoprase for hundreds of years.
• Queensland, Australia. Australia is the leading producer today, and much of the best material comes from the Marlborough Creek District.
• Western Australia. The International Gem Society lists Yandramindra, Wingelina and Kalgoorlie, and Geology.com adds deposits in New South Wales and South Australia.
• Elsewhere. Tanzania, Kazakhstan, Madagascar, India, Brazil, the Czech Republic, Slovakia, Russia, and Arizona and California in the United States. Tanzanian material often reads more bluish or turquoise green than the classic Australian apple tone.

What is "lemon chrysoprase", really?

Mostly magnesite, magnesium carbonate (MgCO3), not chalcedony. Geology.com calls it a milky green rock composed mainly of magnesite that forms where serpentine is weathered or altered by hydrothermal activity, and suggests "lemon magnesite" or "citron magnesite" as the honest names. The confusion is understandable: the two materials come out of the same peridotite and serpentine rocks in Australia, lemon magnesite and chrysoprase often share the same fractures and nodules, and a nodule can have a chrysoprase core overgrown by magnesite or the reverse. Many rough pieces are a genuine mix.

For a buyer the difference is durability and identity, and both are easy to check:

Hardness and gravity for magnesite are from Minerals.net on magnesite; Webmineral gives a measured specific gravity of 2.98. A stone of the same size will therefore feel noticeably heavier in the hand if it is magnesite. Magnesite also reacts to acid, but only weakly: Geology.com says it effervesces in room-temperature dilute hydrochloric acid when powdered, so a drop on a polished face may show nothing. Rely on hardness, weight and translucency instead.

Lemon magnesite is an attractive, inexpensive stone and is fine as a palm stone or bead you handle gently. The problem is only the name, which suggests a hard, rare quartz when the material is a soft carbonate.

How do you spot dyed chalcedony sold as chrysoprase?

This is the bigger trap, because the dyed stone really is chalcedony and passes hardness and gravity tests. Minerals.net states plainly that white chalcedony can easily be dyed to look like chrysoprase, and Geology.com reports that dyed green chalcedony and agate are often sold as "chrysoprase", "chalcedony chrysoprase" or "chrysoprase chalcedony". All of those are misnomers; the correct name is dyed green chalcedony. Run these checks in order:

1. Look for perfection. Natural chrysoprase usually shows some variation in color, saturation or translucency and often contains small inclusions. A strand of beads with identical color, clarity and saturation is, in Geology.com's words, either imitation, dyed or of fantastic quality, and the price will tell you which.
2. Check cracks, pits and drill holes with a 10x loupe. Dye travels along open paths, so color pooled in fractures or concentrated around a bead hole is a strong sign.
3. Judge the hue. Natural nickel green sits between yellowish green and apple green. A cool emerald or jade-like green, very saturated in thin pieces, is suspicious.
4. Use a Chelsea filter. The International Gem Society notes that dyed blue and green chalcedony shows pink in a Chelsea filter. Nickel-colored chrysoprase should stay green. A cheap filter is worth carrying to shows if you buy green stones.
5. Ask directly. A seller who answers "yes, it is dyed" is being honest. Treat any listing that says only "green chrysoprase" at bargain bead prices as dyed until shown otherwise. More on this pattern in dyed stones.

How does chrysoprase compare with jade, prehnite and chrome chalcedony?

Four green stones get mixed up at the bead counter. A quick guide:

Jade values come from Geology.com on jade and prehnite values from Minerals.net on prehnite. Minerals.net sums up the chrysoprase side: jade is usually less translucent, prehnite is less intensely colored with a more yellowish hue, and chrome chalcedony is generally darker. Geology.com places mtorolite in Zimbabwe and a similar Bolivian material called chiquitanita. For the jade comparison in depth, see chrysoprase vs jade, and for the yellow-green look-alike, prehnite.

One name collision deserves its own line: chrysocolla is a copper silicate, Cu2H2Si2O5(OH)4, with a hardness of 2 to 4 according to Minerals.net on chrysocolla. It is blue to blue-green rather than apple green and has nothing to do with chrysoprase apart from the "chryso" prefix.

Does chrysoprase fade?

Some of it can. Geology.com notes that color in some specimens is unstable and that prolonged sunlight can fade it; heat can do the same, so jewelers are warned not to heat the stone during repair. Minerals.net gives the same caution about repeated light exposure. Practical care:

• Display away from a sunny windowsill or under strong lamps for long periods.
• Store it in a drawer or box, away from heaters.
• Clean with warm water and mild soap; it is hard enough for everyday handling, but avoid ultrasonic cleaners on cracked pieces.
• Lemon magnesite needs more care: no acids, and keep it away from harder stones that will scratch it.

What is chrysoprase associated with in crystal traditions?

The name comes from Greek words for "golden apple" or "golden leek". In crystal traditions chrysoprase is associated with optimism, renewal and the heart, which is largely a reflection of its spring-green color. These are beliefs, not physical properties.

Shopping the chrysoprase we stock

Price for chrysoprase is driven by saturation, evenness and translucency: a rich apple green that glows when backlit costs much more than a pale or cloudy piece, and because rough comes from narrow veins, large clean pieces carry a premium. In tumbled and polished specimens, a little color zoning and some brown matrix are signs of a natural stone, not flaws to avoid. Hold any piece up to a light: real chrysoprase transmits a green glow at its thinner edges.

• POLISHED CHRYSOPRASE Specimens: small polished pieces of natural chrysoprase. Look for the apple green tone with slight variation from piece to piece, which is what natural nickel color looks like.
• Polished Chrome Chalcedony, Mtorolite: the chromium-colored chalcedony from Zimbabwe. Buy one alongside chrysoprase to see the difference: darker, greyer green and far less translucent.
• Prehnite: the softer yellow-green look-alike, useful as a side-by-side reference for hue and luster.
• Chrysocolla: the copper mineral with the similar name; blue-green and much softer, a good example of why names alone mislead.

If a listing anywhere calls an opaque yellow-green stone "lemon chrysoprase", read it as magnesite, and if a green "chrysoprase" is flawless and cheap, read it as dyed.

Frequently asked questions

Is lemon chrysoprase real chrysoprase?

No. Lemon or citron chrysoprase is mainly magnesite, a magnesium carbonate with a hardness of about 3.5 to 4.5 and a specific gravity near 3.0. Real chrysoprase is nickel-colored chalcedony at Mohs 7. The two often occur together in Australian deposits, which is how the trade name started.

How can I tell if chrysoprase is dyed?

Check for perfectly uniform color across many beads, color gathered in cracks or drill holes, and an emerald or jade-like hue instead of apple green. Under a Chelsea filter, dyed green chalcedony shows pink while nickel-colored chrysoprase stays green. Very low prices for large, flawless pieces are another warning.

Where does the best chrysoprase come from?

Australia is the leading producer, and much of the finest apple-green material comes from the Marlborough Creek District of Queensland. Western Australia, Tanzania, Kazakhstan and Brazil also produce it, and Szklary in Poland was the classic historical source for centuries.

Will chrysoprase fade in the sun?

Some specimens can. Prolonged exposure to sunlight or to heat can pale the green, so it is sensible to display chrysoprase out of direct sun, keep it away from heaters, and ask a jeweler not to heat the stone during repairs.

Is chrysoprase a type of jade?

No. Chrysoprase is chalcedony, a microcrystalline quartz, while jade is jadeite or nephrite. Jade is heavier, with a specific gravity of 3.0 to 3.5 against about 2.64 for chrysoprase, and it is usually less translucent with a granular or fibrous texture.

Sources

• Geology.com, Chrysoprase: https://geology.com/gemstones/chrysoprase/
• Minerals.net, The gemstone chrysoprase: https://www.minerals.net/gemstone/chrysoprase_gemstone.aspx
• International Gem Society, Chalcedony Value, Price, and Jewelry Information: https://www.gemsociety.org/article/chalcedony-jewelry-and-gemstone-information/
• Minerals.net, The mineral magnesite: https://www.minerals.net/mineral/magnesite.aspx
• Webmineral, Magnesite Mineral Data: https://webmineral.com/data/Magnesite.shtml
• Geology.com, Magnesite: https://geology.com/minerals/magnesite.shtml
• Geology.com, Jade: https://geology.com/gemstones/jade/
• Minerals.net, The gemstone prehnite: https://www.minerals.net/gemstone/prehnite_gemstone.aspx
• Minerals.net, The mineral chrysocolla: https://www.minerals.net/mineral/chrysocolla.aspx