Apophyllite is highly prized by collectors for its brilliant, mirror-like pearly luster on cleavage faces and clear, geometric tetragonal crystals. It is most frequently encountered in basaltic vugs where it forms stunning, water-clear prismatic clusters alongside zeolites.
Is this apophyllite?
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 apophyllite with a known reference. Apophyllite sits at Mohs 4.5-5 — softer than the next harder reference, harder than the previous one.
- 2Check the streakDrag the specimen across an unglazed porcelain plate. Apophyllite leaves a white streak.
- 3Read the lusterHold the specimen under a strong light. Apophyllite typically shows a vitreous to pearly luster.
- 4Match the color rangeCompare against the expected color range: white, colorless, green, pink, yellow.
- 5Look at form & habitCrystal system: tetragonal. Typical habit: prismatic crystals, blocky, tabular, or as drusy crusts.
Often confused with
Apophyllite vs. its common look-alikes — and how to tell them apart in the field.
How to tell apart: Luster reads vitreous to pearly on Apophyllite and vitreous on Stilbite.
How to tell apart: Quartz is the harder of the two (Mohs 7 vs. 4.5-5); luster reads vitreous to pearly on Apophyllite and vitreous on Quartz.
Often found alongside apophyllite
Minerals reported to co-occur with apophyllite. Spotting these in float or country rock is a strong cue you are in the right ground.
All properties
- Chemical formula
- KCa₄(Si₈O₂₀)(F,OH)·8H₂O
- Mohs hardness
- 4.5-5
- Density
- 2.3-2.5 g/cm³
- Streak
- White
- Luster
- Vitreous to Pearly
- Transparency
- Transparent
- Crystal system
- Tetragonal
- Crystal habit
- Prismatic Crystals, Blocky, Tabular, Or as Drusy Crusts
- Cleavage
- Perfect Basal
- Rarity
- Common
- Uses
- Collector, Decorative
- Host rock
- Basalt Cavities, Volcanic Amygdules
- Typical price
- $10-100 thumbnail, $50-500 cabinet specimen
Where rockhounds find apophyllite
6 mapped spotsClassic worldwide localities
- Pune, India
- Teigarhorn, Iceland
- Kongsberg, Norway
- Copper Falls, USA
- Mont Saint-Hilaire, Canada
Field-hunting tip
Look in basalt cavities, volcanic amygdules country — that is the host setting where apophyllite typically forms. If you start seeing heulandite, stilbite, thomsonite in float, you are in the right ground. Field specimens usually show a prismatic crystals, blocky, tabular, or as drusy crusts habit, so train your eye for that shape before scanning the outcrop. In the U.S., the densest reported localities are in California, Colorado, New Jersey — start trip planning there.
Common questions
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Find apophyllite on the map
RockHoundR shows mapped rockhounding spots, access rules, and lets you log every find.
