Heulandite-Ca is a common member of the zeolite group, best recognized by its characteristic 'coffin-shaped' tabular crystals. It is frequently found in the cavities of basaltic rocks, often occurring in dense, attractive clusters associated with other zeolites and minerals like stilbite or apophyllite.
Is this heulandite-ca?
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 heulandite-ca with a known reference. Heulandite-Ca sits at Mohs 3.5-4 — softer than the next harder reference, harder than the previous one.
- 2Check the streakDrag the specimen across an unglazed porcelain plate. Heulandite-Ca leaves a white streak.
- 3Read the lusterHold the specimen under a strong light. Heulandite-Ca typically shows a vitreous luster.
- 4Match the color rangeCompare against the expected color range: white, colorless, pink, orange, brown.
- 5Look at form & habitCrystal system: monoclinic. Typical habit: tabular crystals with coffin-like outline.
Often confused with
Heulandite-Ca vs. its common look-alikes — and how to tell them apart in the field.
Often found alongside heulandite-ca
Minerals reported to co-occur with heulandite-ca. Spotting these in float or country rock is a strong cue you are in the right ground.
All properties
- Chemical formula
- (Ca,Na,K)₅(Si₂₇Al₉)O₇₂·26H₂O
- Mohs hardness
- 3.5-4
- Density
- 2.1-2.2 g/cm³
- Streak
- White
- Luster
- Vitreous
- Transparency
- Translucent
- Crystal system
- Monoclinic
- Crystal habit
- Tabular Crystals with Coffin-like Outline
- Cleavage
- Perfect Basal
- Rarity
- Common
- Uses
- Collector, Specimen
- Host rock
- Basalt Cavities and Amygdules
- Typical price
- $10-150 depending on specimen size and clarity
Where rockhounds find heulandite-ca
Classic worldwide localities
- India
- Iceland
- Italy
- USA
- Scotland
Field-hunting tip
Look in basalt cavities and amygdules country — that is the host setting where heulandite-ca typically forms. If you start seeing stilbite, apophyllite, calcite in float, you are in the right ground. Field specimens usually show a tabular crystals with coffin-like outline habit, so train your eye for that shape before scanning the outcrop.
Common questions
How do you identify heulandite-ca?+
Where is heulandite-ca found?+
How much is heulandite-ca worth?+
What rocks look like heulandite-ca?+
What minerals are found with heulandite-ca?+
What kind of rock does heulandite-ca form in?+
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Find heulandite-ca on the map
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