Pectolite is best known for its acicular, radiating crystal clusters and as the primary component of the gemstone Larimar. It is commonly found in cavities of basaltic rocks, where it forms delicate fibrous sprays that can be very attractive for collectors.
Is this pectolite?
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 pectolite with a known reference. Pectolite 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. Streak: white.
- 3Read the lusterHold the specimen under a strong light. Luster: silky, subvitreous.
- 4Match the color rangeCompare against the expected color range: white, gray, pale green, blue, yellowish, gray, light pink, light green.
- 5Look at form & habitCrystal system: triclinic. Typical habit: acicular, globular, radial.
Often confused with
Pectolite vs. its common look-alikes, and how to tell them apart in the field.
How to tell apart: Luster reads silky, subvitreous on Pectolite and vitreous, pearly on cleavage on Wollastonite.
How to tell apart: Luster reads silky, subvitreous on Pectolite and vitreous to pearly on Natrolite.
How to tell apart: Prehnite is the harder of the two (Mohs 6-6.5 vs. 4.5-5); luster reads silky, subvitreous on Pectolite and vitreous, weak pearly on {001} on Prehnite.
Often found alongside pectolite
Minerals reported to co-occur with pectolite. Spotting these in float or country rock is a strong cue you are in the right ground.
All properties
- Chemical formula
- NaCa₂Si₃O₈(OH)
- Mohs hardness
- 4.5-5
- Density
- 2.84-2.90 g/cm³
- Streak
- White
- Luster
- Silky, subvitreous
- Transparency
- Translucent to opaque
- Crystal system
- Triclinic
- Crystal habit
- Acicular, globular, radial
- Cleavage
- Perfect on {100} and {001}
- Fluorescence
- Pink under SW UV; orange-pink under LW UV
- Rarity
- Uncommon
- Uses
- Collector, Lapidary
- Host rock
- A primary mineral in nepheline syenites
Where rockhounds find pectolite
2 mapped spotsClassic worldwide localities
- Paterson, Passaic Co., and Bergen Hill, Hudson Co., New Jersey, USA
- Magnet Cove, Hot Spring Co., and on Granite Mountain, near Little Rock, Pulaski Co., Arkansas, USA
- Mt. Baldo and Mt. Monzoni, Trentino-Alto Adige, Italy
- Niederkirchen, near Wolfstein, and Rauschermühle, Rhineland-Palatinate, Germany
- Lendalfoot, Ayrshire, Scotland
- Zlto, Sweden
Field-hunting tip
Where it forms: A primary mineral in nepheline syenites. If you start seeing zeolites, datolite, prehnite in float, you are in the right ground. Typical habit: acicular, globular, radial. Train your eye for that shape before scanning the outcrop. In the U.S., the densest reported localities are in California, New Jersey. Start trip planning there.
Common questions
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Find pectolite on the map
RockHoundR shows mapped rockhounding spots, access rules, and lets you log every find.
