Prase Identification Guide
A field guide to prase, a leek-green quartz, identifying its dull green color, quartz hardness, and how to separate it from chrysoprase, aventurine, and jade.
Read the full Prase encyclopedia entry →
What Prase Looks Like
Prase is a dull leek-green to grayish-green variety of quartz, colored by included green minerals such as actinolite, hedenbergite, or chlorite fibers rather than by dissolved chemistry. It can be macrocrystalline quartz or microcrystalline (chalcedonic) and is translucent to opaque with a vitreous to greasy luster. The green tends to be muted and somewhat earthy compared to the bright apple-green of chrysoprase.
Step-by-Step Field ID Checklist
- Confirm quartz. Hardness 7 (scratches glass and steel), no cleavage, conchoidal fracture.
- Note the muted green. A dull leek-green to grayish-green tone points to prase rather than vivid chrysoprase.
- Look for included fibers. Under magnification, green amphibole/chlorite needles or flakes may be visible as the colorant.
- Check translucency. Translucent to opaque; hold to light to see depth.
- Test with a knife. It will not be scratched by steel (rules out softer green stones).
Key Diagnostic Tests
- Mohs hardness: 7 — scratches glass and steel.
- Cleavage: None; conchoidal fracture.
- Streak: White.
- Specific gravity: About 2.6.
- Acid: No reaction to dilute HCl.
- Inclusions: Green silicate fibers/flakes cause the color (not iron or nickel in solution).
Common Look-Alikes and How to Tell Them Apart
- Chrysoprase: Bright apple-green chalcedony colored by nickel; prase is duller, grayer, and colored by mineral inclusions. Chrysoprase is more uniformly translucent.
- Aventurine (green quartz): Shows glittery aventurescence from mica/fuchsite flakes; prase lacks that sparkle.
- Jade (nephrite/jadeite): Tougher (resists chipping), nephrite is softer (6–6.5) and fibrous; prase is harder quartz with conchoidal fracture.
- Green jasper: Opaque and often patterned; prase is more translucent and evenly colored.
- Prasiolite (green amethyst): A transparent leek-green quartz colored by heat treatment; prase owes its color to inclusions and is more opaque.
Where Prase Is Found
Prase occurs where quartz crystallized with green silicate minerals, often in metamorphic and skarn environments. Classic localities include Serifos (Greece), the Austrian Alps, Finland, and parts of the western United States. It has been used as a minor ornamental stone since antiquity.
Frequently asked questions
What is prase?
Prase is a dull leek-green to grayish-green variety of quartz colored by included green minerals like actinolite, hedenbergite, or chlorite, rather than by dissolved chemistry.
How can you tell if it's real prase?
Confirm quartz hardness of 7 (scratches glass and steel), no cleavage with conchoidal fracture, a muted green color, white streak, and no acid reaction. Green fibrous inclusions under magnification support the ID.
Prase vs chrysoprase: what is the difference?
Chrysoprase is a bright apple-green chalcedony colored by nickel, while prase is a duller, grayer green quartz colored by green mineral inclusions.
Prase vs prasiolite: how do you tell them apart?
Prasiolite is a transparent leek-green quartz produced by heat-treating amethyst, while prase is more opaque and gets its green from mineral inclusions, not treatment.
Prase identified by the community
Recent Prase specimens identified with Rock Identifier.
