Mesolite is a delicate zeolite mineral often found as fine, needle-like acicular crystals or radiating sprays within basalt vesicles. It is visually very similar to natrolite and scolecite, usually requiring lab tests or specific crystal habit analysis to differentiate confidently from its zeolite cousins.
Is this mesolite?
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 mesolite with a known reference. Mesolite 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. Streak: white.
- 3Read the lusterHold the specimen under a strong light. Luster: vitreous, silky when fibrous.
- 4Match the color rangeCompare against the expected color range: white, colorless, gray, pale yellow.
- 5Look at form & habitCrystal system: orthorhombic. Typical habit: acicular, capillary, spherical.
Often confused with
Mesolite vs. its common look-alikes, and how to tell them apart in the field.
Often found alongside mesolite
Minerals reported to co-occur with mesolite. Spotting these in float or country rock is a strong cue you are in the right ground.
All properties
- Chemical formula
- Na₂Ca₂Si₉Al₆O₃₀·8H₂O
- Mohs hardness
- 5
- Density
- 2.26 g/cm³
- Streak
- White
- Luster
- Vitreous, silky when fibrous
- Transparency
- Transparent to translucent, opaque
- Crystal system
- Orthorhombic
- Crystal habit
- Acicular, capillary, spherical
- Cleavage
- {110}, {110}, perfect
- Rarity
- Uncommon
- Uses
- Collector, Scientific research
- Host rock
- In cavities of volcanic rocks, typically basalt, also in andesites, porphyries, and hydrothermal veins
Where rockhounds find mesolite
3 mapped spotsClassic worldwide localities
- Table Mountain, Jefferson Co., Colorado, USA
- Skookumchuck Dam, near Bucoda, Thurston Co., Washington, USA
- Goble, Columbia Co., Oregon, USA
- Dollar, and on Shotgun Creek, Linn Co., Oregon, USA
- North Mountain and Gates Mountain, and at Cape Blomiden, Nova Scotia, Canada
- Puy de Marman, near Veyre, Puy-de-Dôme, France
Field-hunting tip
Where it forms: In cavities of volcanic rocks, typically basalt, also in andesites, porphyries, and hydrothermal veins. If you start seeing natrolite, scolecite, calcite in float, you are in the right ground. Typical habit: acicular, capillary, spherical. Train your eye for that shape before scanning the outcrop. In the U.S., the densest reported localities are in Michigan, Oregon. Start trip planning there.
Common questions
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Find mesolite on the map
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