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Prasiolite: The Leek-Green Quartz Sold as Green Amethyst

By Digital Towns Crystals · Last reviewed October 8, 2026

Short answer: prasiolite is pale yellowish green to leek-green quartz. Almost all of it starts as amethyst from a handful of deposits, chiefly Montezuma in Minas Gerais, Brazil, that turns green when heated to around 500 °C. Naturally green prasiolite exists but is a collector rarity. It is as hard as any quartz (Mohs 7) but its color can fade in strong light or heat, and U.S. trade rules treat "green amethyst" as a misleading name for it.

What is prasiolite, exactly?

Prasiolite is a color variety of quartz, silicon dioxide (SiO2), in the trigonal system. Its physical constants are quartz constants: GIA's amethyst entry, which covers the same mineral, gives a refractive index of 1.544 to 1.553, birefringence 0.009, specific gravity 2.66 and Mohs hardness 7. Webmineral's quartz data lists a specific gravity of 2.65. Nothing in those numbers separates prasiolite from amethyst or citrine; the difference is purely color, and color in this family is about the state of trace iron in the crystal.

The name comes from Greek. Geology.com explains it combines prason, which means "leek," and lithos, which means "stone," and records the alternate spellings "praseolite" and "praziolite." It is pronounced PRAYS-ee-oh-light. The leek reference is accurate: good prasiolite is a soft, slightly yellowish green, never the saturated green of emerald or tsavorite.

Why is "green amethyst" the wrong name?

Amethyst is by definition the purple variety of quartz, so a green stone cannot be amethyst. That is more than pedantry. The Federal Trade Commission's Guides for the Jewelry, Precious Metals, and Pewter Industries, at 16 CFR 23.26, list misleading varietal names, and the second example is explicit: "Use of the term 'green amethyst' to describe prasiolite" (eCFR, 16 CFR Part 23). The first example in the same list is "yellow emerald" for golden beryl or heliodor.

Geology.com's amethyst article notes that sellers who keep using the name risk legal action from customers or the FTC. In practice the term survives in jewelry advertising because buyers recognize "amethyst," and Minerals.net acknowledges that green amethyst is how the stone is more commonly known in the gem trade. Treat a listing that says "green amethyst" as a seller choosing marketing over accuracy, not as a different stone.

Where does prasiolite come from?

Only certain amethyst converts. Geology.com states that only a few amethyst localities in the world are known to have amethyst that turns to prasiolite on heating, and that most prasiolite entering the gem market today is made by heating amethyst and yellow quartz from the Montezuma deposit in Minas Gerais, Brazil. Minerals.net also names the Montezuma Mine as the deposit known for producing the green variety after heat treatment.

Source How the green forms Market importance
Montezuma deposit, Minas Gerais, Brazil Heating mined amethyst and yellow quartz Main commercial source
An Arizona amethyst deposit Heating Minor
Some Polish amethyst Irradiation Minor, lighter green
Near Susanville, California Natural heating by a younger lava flow Collector rarity
Sokolowiec area, Lower Silesia, Poland Naturally green quartz, color attributed to iron Collector rarity

The natural deposits

The California occurrence is a neat piece of geology. According to Geology.com, drawing on a 1982 Gems & Gemology paper by Thomas Paradise, amethyst grew in cavities of a solidified lava flow, took its purple from natural radiation, and was later baked when another lava flow covered it, converting some of it into natural prasiolite. The material sits in talus below steep exposures of metavolcanic basalt and andesite. In Poland's Kaczawskie Mountains, green quartz occurs as crystals in amygdules and as the crystalline core of agate nodules.

Neither natural source supplies the trade in any volume. A "natural prasiolite" label should come with a specific locality, and anything priced like ordinary Brazilian stock is almost certainly heated.

How is prasiolite made from amethyst?

In short: a kiln, a few hundred degrees, and the right starting rock. Geology.com reports that most amethyst turns yellow at about 470 °C and dark yellow to reddish brown around 550 °C, while a small number of deposits give yellowish green to green material at about 500 °C. A smaller share is produced by irradiating amethyst, which yields a lighter green that can be lost above roughly 150 °C. The detailed mechanics of heat treatment, and how it relates to citrine, are covered in the heat-treated crystals guide and the citrine guide; the point for a prasiolite buyer is simply that treated is normal for this stone.

Does prasiolite fade?

It can. Geology.com warns that heat-produced prasiolite exposed to strong sunlight and some artificial light for long periods can lose its green, and recommends storing it in darkness. It should not be stored near heaters or left in a hot car, and a jeweler should remove it from its setting before soldering. The irradiated kind is the more fragile of the two because of its low fading temperature.

Practical care:

  • Display prasiolite spheres and points out of direct sun; a shaded shelf or closed cabinet is fine.
  • Keep jewelry in a closed box between wearings.
  • Clean with lukewarm soapy water and a soft brush; avoid steam cleaners and any heat.
  • Hardness 7 means it resists scratching well, so wear is less of a concern than color.

The broader list of light-sensitive stones is in the sun-fading guide.

How do you tell prasiolite from other green quartz and lookalikes?

Several green materials get mixed up with it:

  • Synthetic green quartz. Geology.com notes that hydrothermal synthetic quartz is made in many greens, some close to prasiolite's leek color, and that some is probably sold as prasiolite without disclosure. Very even color in large, flawless pieces at low prices is the warning sign; the synthetic quartz guide covers the lab clues.
  • Chrysoprase. Translucent chalcedony with a bright apple green from nickel. It is milky rather than transparent, which separates it at a glance.
  • Green aventurine. Quartz with sparkling fuchsite mica flakes. The glitter gives it away.
  • Dyed quartz. Dye concentrates in fractures and cavities and may come off with mild solvents.
  • Prase. Webmineral lists prase as leek green chalcedony, a different, opaque to translucent material despite the similar name.

Transparent prasiolite often shows faint angular color zoning inherited from the amethyst it came from. Looking through a stone table-down on white paper makes those zones easier to see.

How is prasiolite graded and priced?

Prasiolite is an affordable quartz, priced well below green beryl or tourmaline of similar size. Value follows color first: Geology.com notes that much prasiolite on the market is light, and that stones of a few carats are normally the ones with a rich green. Small stones can look nearly colorless. After color, buyers weigh transparency, freedom from visible inclusions, and for spheres and carvings the quality of the polish and the evenness of the green.

What is prasiolite associated with in crystal traditions?

In crystal traditions, prasiolite is associated with the heart chakra, renewal and growth, borrowing symbolism from both its green color and its link to amethyst. Practitioners often pair it with amethyst for that reason.

Shopping for prasiolite

Ask three questions of any listing: does it use the name prasiolite rather than "green amethyst," does it disclose heat, and does it state an origin. Brazil is the expected answer. Then judge the green: you want a clear leek green that holds across the piece, not a near-colorless stone with a faint tint.

  • Prasiolite: Brazilian prasiolite offered as polished spheres from about 38 mm to 48 mm. Spheres show color depth well, since light travels through the full diameter; compare sizes, because the larger spheres read greener.
  • Amethyst - Cut Base: Brazilian amethyst points with polished cut bases, around 2 by 2 by 2.5 inches. Useful as the "before" stone, the purple quartz that prasiolite is made from.
  • Citrine Tumbles: small tumbled citrine, the yellow sibling produced from amethyst at slightly different temperatures. Set beside prasiolite and amethyst, the three show how one mineral changes color with heat.

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Frequently asked questions

Is prasiolite natural or man-made?

The quartz is natural; the green color is usually produced by heating natural amethyst at about 500 °C. Naturally green prasiolite exists, for example near Susanville, California, and in Lower Silesia, Poland, but it is rare and not an important part of the market.

Is green amethyst the same as prasiolite?

Yes, they are the same material, but "green amethyst" is an incorrect name. The FTC jewelry guides (16 CFR 23.26) list "green amethyst" for prasiolite as an example of a misleading varietal name. Prasiolite is the correct term.

Will prasiolite lose its color?

It can fade with long exposure to strong sunlight and some artificial light, and heat can also affect it. Irradiated prasiolite can lose its color above roughly 150 °C. Store it in the dark and keep it away from heat sources.

How hard is prasiolite?

Prasiolite is quartz, so it is Mohs 7 with no cleavage. It is durable enough for rings and bracelets, with the same wearing qualities as amethyst and citrine. Fading, not scratching, is the main care concern.

Why is my prasiolite so pale?

Pale color is normal. Much prasiolite on the market is light, and small stones barely show their green. Larger pieces, like spheres and stones of several carats, show deeper color because light passes through more material.

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