Natrolite is a widely sought-after zeolite known for its beautiful, delicate needle-like or hair-like crystal sprays. Collectors should look for radiating clusters inside basalt cavities, often associated with other secondary minerals like apophyllite or analcime.
Is this natrolite?
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 natrolite with a known reference. Natrolite sits at Mohs 5-5.5, 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: vitreous to pearly.
- 4Match the color rangeCompare against the expected color range: white, colorless, gray, yellow, red, pink, yellowish white, reddish white.
- 5Look at form & habitCrystal system: orthorhombic. Typical habit: acicular, nodular, prismatic.
Often confused with
Natrolite vs. its common look-alikes, and how to tell them apart in the field.
Often found alongside natrolite
Minerals reported to co-occur with natrolite. Spotting these in float or country rock is a strong cue you are in the right ground.
All properties
- Chemical formula
- Na₂Al₂Si₃O₁₀·2H₂O
- Mohs hardness
- 5-5.5
- Density
- 2.20-2.26 g/cm³
- Streak
- White
- Luster
- Vitreous to pearly
- Transparency
- Transparent to translucent
- Crystal system
- Orthorhombic
- Crystal habit
- Acicular, nodular, prismatic
- Cleavage
- {110}, perfect; parting on {010}
- Fluorescence
- Yellow-orange pale green under SW UV; yellow-orange greenish white under LW UV
- Rarity
- Common
- Uses
- Collector, Scientific study
- Host rock
- In cavities in amygdaloidal basalts and related igneous rocks, one of the last minerals to form; fills seams in granite, gneiss, and syenite
Where rockhounds find natrolite
4 mapped spotsClassic worldwide localities
- Bergen Hill, Hudson Co., at Prospect Park, Passaic Co., and in the Chimney Rock quarry, Bound Brook, Passaic Co., New Jersey, USA
- North of Livingstone, Park Co., Montana, USA
- Springfield, Lane Co., Oregon, USA
- Gem mine, San Benito Co., California, USA
- Höwenegg quarry, Hegau, Baden-Württemberg, Germany
- Puy de Marman, near Veyre, Puy-de-Dôme, France
Field-hunting tip
Where it forms: In cavities in amygdaloidal basalts and related igneous rocks, one of the last minerals to form; fills seams in granite, gneiss, and syenite. If you start seeing zeolites, calcite, nepheline in float, you are in the right ground. Typical habit: acicular, nodular, prismatic. Train your eye for that shape before scanning the outcrop. In the U.S., the densest reported localities are in Michigan, Montana, New Jersey. Start trip planning there.
Common questions
How do you identify natrolite?+
Where is natrolite found?+
Can I find natrolite in the United States?+
What rocks look like natrolite?+
What minerals are found with natrolite?+
What kind of rock does natrolite form in?+
What is natrolite used for?+
Find natrolite on the map
RockHoundR shows mapped rockhounding spots, access rules, and lets you log every find.
