Gonnardite is a rare zeolite mineral that frequently occurs as radiating fibrous or acicular sprays within basaltic cavities. It is visually similar to other fibrous zeolites like natrolite, and often requires advanced testing or association context to distinguish it in the field.
Is this gonnardite?
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 gonnardite with a known reference. Gonnardite sits at Mohs 5 — softer than the next harder reference, harder than the previous one.
- 2Check the streakDrag the specimen across an unglazed porcelain plate. Gonnardite leaves a white streak.
- 3Read the lusterHold the specimen under a strong light. Gonnardite typically shows a vitreous luster.
- 4Match the color rangeCompare against the expected color range: white, colorless, yellow, pinkish.
- 5Look at form & habitCrystal system: orthorhombic. Typical habit: acicular, fibrous, radiating clusters, massive.
Often confused with
Gonnardite vs. its common look-alikes — and how to tell them apart in the field.
Often found alongside gonnardite
Minerals reported to co-occur with gonnardite. Spotting these in float or country rock is a strong cue you are in the right ground.
All properties
- Chemical formula
- Na₂CaAl₄Si₆O₂₀·7H₂O
- Mohs hardness
- 5
- Density
- 2.26 g/cm³
- Streak
- White
- Luster
- Vitreous
- Transparency
- Translucent
- Crystal system
- Orthorhombic
- Crystal habit
- Acicular, Fibrous, Radiating Clusters, Massive
- Cleavage
- Distinct
- Rarity
- Uncommon
- Uses
- Collector
- Host rock
- Basaltic Vugs and Cavities
- Typical price
- $10-60 for cabinet specimens
Where rockhounds find gonnardite
Classic worldwide localities
- France
- Czech Republic
- Canada
- USA
- Iceland
Field-hunting tip
Look in basaltic vugs and cavities country — that is the host setting where gonnardite typically forms. If you start seeing natrolite, calcite, analcime in float, you are in the right ground. Field specimens usually show a acicular, fibrous, radiating clusters, massive habit, so train your eye for that shape before scanning the outcrop.
Common questions
How do you identify gonnardite?+
Where is gonnardite found?+
How much is gonnardite worth?+
What rocks look like gonnardite?+
What minerals are found with gonnardite?+
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Find gonnardite on the map
RockHoundR shows mapped rockhounding spots, access rules, and lets you log every find.
