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 — that is 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.
