Epistilbite is a zeolite mineral known for its distinctive twinned, blade-like prismatic crystals. It is most easily recognized by its heart-shaped or V-shaped twinning and its occurrence in volcanic vugs alongside other zeolites.
Is this epistilbite?
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 epistilbite with a known reference. Epistilbite sits at Mohs 4-5, softer than the next harder reference, harder than the previous one.
- 2Check the streakDrag the specimen across an unglazed porcelain plate. Epistilbite leaves a white streak.
- 3Read the lusterHold the specimen under a strong light. Epistilbite typically shows a vitreous luster.
- 4Match the color rangeCompare against the expected color range: white, colorless, yellowish, pinkish.
- 5Look at form & habitCrystal system: monoclinic. Typical habit: prismatic crystals, often forming V-shaped or heart-shaped twins.
Often confused with
Epistilbite vs. its common look-alikes, and how to tell them apart in the field.
Often found alongside epistilbite
Minerals reported to co-occur with epistilbite. Spotting these in float or country rock is a strong cue you are in the right ground.
All properties
- Chemical formula
- (Ca,Na₂,K₂)₃(Si₁₈Al₆)O₄₈·16H₂O
- Mohs hardness
- 4-5
- Density
- 2.25 g/cm³
- Streak
- White
- Luster
- Vitreous
- Transparency
- Translucent
- Crystal system
- Monoclinic
- Crystal habit
- Prismatic Crystals, Often Forming V-shaped or Heart-shaped Twins
- Cleavage
- Perfect On {010}
- Rarity
- Uncommon
- Uses
- Collector, Scientific Research
- Host rock
- Basaltic Vugs and Cavities
- Typical price
- $15-80 thumbnail/miniature specimens
Where rockhounds find epistilbite
Classic worldwide localities
- Poona, India
- Teigarhorn, Iceland
- Nova Scotia, Canada
- Faeroe Islands
Field-hunting tip
Look in basaltic vugs and cavities country, the host setting where epistilbite typically forms. If you start seeing heulandite, stilbite, apophyllite in float, you are in the right ground. Field specimens usually show a prismatic crystals, often forming v-shaped or heart-shaped twins habit, so train your eye for that shape before scanning the outcrop.
Common questions
How do you identify epistilbite?+
Where is epistilbite found?+
How much is epistilbite worth?+
What rocks look like epistilbite?+
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Find epistilbite on the map
RockHoundR shows mapped rockhounding spots, access rules, and lets you log every find.
