Laumontite is a common zeolite mineral known for forming delicate, prismatic crystal clusters in basaltic cavities. It is notable for its tendency to dehydrate rapidly upon exposure to air, often turning chalky or crumbling into a powder, so collectors should store specimens in a humidified environment.
Is this laumontite?
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 laumontite with a known reference. Laumontite sits at Mohs 4 — softer than the next harder reference, harder than the previous one.
- 2Check the streakDrag the specimen across an unglazed porcelain plate. Laumontite leaves a white streak.
- 3Read the lusterHold the specimen under a strong light. Laumontite typically shows a vitreous luster.
- 4Match the color rangeCompare against the expected color range: white, colorless, yellow, orange, pink.
- 5Look at form & habitCrystal system: monoclinic. Typical habit: prismatic crystals, radial clusters, fibrous aggregates.
Often confused with
Laumontite vs. its common look-alikes — and how to tell them apart in the field.
Often found alongside laumontite
Minerals reported to co-occur with laumontite. Spotting these in float or country rock is a strong cue you are in the right ground.
All properties
- Chemical formula
- CaAl₂Si₄O₁₂·4H₂O
- Mohs hardness
- 4
- Density
- 2.25-2.36 g/cm³
- Streak
- White
- Luster
- Vitreous
- Transparency
- Translucent
- Crystal system
- Monoclinic
- Crystal habit
- Prismatic Crystals, Radial Clusters, Fibrous Aggregates
- Cleavage
- Perfect in Two Directions
- Rarity
- Common
- Uses
- Collector, Scientific Research
- Host rock
- Amygdaloidal Basalt Cavities, Hydrothermal Veins, Volcanic Rocks
- Typical price
- $10-60 per specimen
Where rockhounds find laumontite
1 mapped spotsClassic worldwide localities
- India
- Italy
- USA
- Scotland
- Czech Republic
Field-hunting tip
Look in amygdaloidal basalt cavities, hydrothermal veins, volcanic rocks country — that is the host setting where laumontite typically forms. If you start seeing heulandite, stilbite, calcite in float, you are in the right ground. Field specimens usually show a prismatic crystals, radial clusters, fibrous aggregates habit, so train your eye for that shape before scanning the outcrop. In the U.S., the densest reported localities are in Wisconsin — start trip planning there.
Common questions
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Find laumontite on the map
RockHoundR shows mapped rockhounding spots, access rules, and lets you log every find.
