Prehnite is best recognized by its characteristic apple-green color and distinct botryoidal or globular habit. It is commonly found as a secondary mineral in the vesicles and cavities of mafic volcanic rocks and is a popular choice for cabochons due to its attractive luster and durability.
Is this prehnite?
5-step field checkRun through these checks against the specimen in your hand. The more boxes tick, the more confident the ID.
- 1Test the hardnessTry to scratch prehnite with a known reference. Prehnite sits at Mohs 6-6.5 — softer than the next harder reference, harder than the previous one.
- 2Check the streakDrag the specimen across an unglazed porcelain plate. Prehnite leaves a white streak.
- 3Read the lusterHold the specimen under a strong light. Prehnite typically shows a vitreous luster.
- 4Match the color rangeCompare against the expected color range: green, yellow-green, white, gray, colorless.
- 5Look at form & habitCrystal system: orthorhombic. Typical habit: botryoidal, globular, reniform, or tabular crystals.
Often confused with
Prehnite vs. its common look-alikes — and how to tell them apart in the field.
How to tell apart: Prehnite is noticeably harder (Mohs 6-6.5 vs. 4-4.5).
How to tell apart: Prehnite is noticeably harder (Mohs 6-6.5 vs. 4.5-5).
How to tell apart: Luster reads vitreous on Prehnite and greasy on Serpentine.
Often found alongside prehnite
Minerals reported to co-occur with prehnite. Spotting these in float or country rock is a strong cue you are in the right ground.
All properties
- Chemical formula
- Ca₂Al₂Si₃O₁₀(OH)₂
- Mohs hardness
- 6-6.5
- Density
- 2.8-3.0 g/cm³
- Streak
- White
- Luster
- Vitreous
- Transparency
- Translucent
- Crystal system
- Orthorhombic
- Crystal habit
- Botryoidal, Globular, Reniform, Or Tabular Crystals
- Cleavage
- Distinct On {001}
- Rarity
- Common
- Uses
- Collector, Lapidary, Ornamental
- Host rock
- Basaltic Volcanic Rocks and Hydrothermal Veins
- Typical price
- $5-50 for specimens, $10-100 for high-quality polished stones
Where rockhounds find prehnite
21 mapped spotsClassic worldwide localities
- South Africa
- Mali
- United States
- Canada
- Australia
U.S. states with prehnite
Each link opens a state-specific list of mapped rockhounding spots that produce prehnite.
Field-hunting tip
Look in basaltic volcanic rocks and hydrothermal veins country — that is the host setting where prehnite typically forms. If you start seeing datolite, calcite, epidote in float, you are in the right ground. Field specimens usually show a botryoidal, globular, reniform, or tabular crystals habit, so train your eye for that shape before scanning the outcrop. In the U.S., the densest reported localities are in New Jersey, Connecticut, Massachusetts — start trip planning there.
Common questions
How do you identify prehnite?+
Where is prehnite found?+
Can I find prehnite in the United States?+
How much is prehnite worth?+
What rocks look like prehnite?+
What minerals are found with prehnite?+
What kind of rock does prehnite form in?+
What is prehnite used for?+
Find prehnite on the map
RockHoundR shows mapped rockhounding spots, access rules, and lets you log every find.
