Natrosilite is an extremely rare sodium silicate mineral found primarily in complex alkaline igneous massifs. Collectors prize it for its rarity and crystal structure, though it is highly sensitive to moisture and can alter or dehydrate if not stored properly.
Is this natrosilite?
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 natrosilite with a known reference. Natrosilite sits at Mohs 3, 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: pearly.
- 4Match the color rangeCompare against the expected color range: colorless, white.
- 5Look at form & habitCrystal system: monoclinic. Typical habit: prismatic crystals, massive.
Often confused with
Natrosilite vs. its common look-alikes, and how to tell them apart in the field.
How to tell apart: Quartz is the harder of the two (Mohs 7 vs. 3); luster reads pearly on Natrosilite and vitreous; waxy to dull when massive on Quartz.
How to tell apart: Natrolite is the harder of the two (Mohs 5-5.5 vs. 3); luster reads pearly on Natrosilite and vitreous to pearly on Natrolite.
Often found alongside natrosilite
Minerals reported to co-occur with natrosilite. Spotting these in float or country rock is a strong cue you are in the right ground.
All properties
- Chemical formula
- Na₂Si₂O₅
- Mohs hardness
- 3
- Density
- 2.48 g/cm³
- Streak
- White
- Luster
- Pearly
- Transparency
- Transparent
- Crystal system
- Monoclinic
- Crystal habit
- Prismatic crystals, massive
- Cleavage
- {100}, perfect micaceous; {001}, distinct; {011}, poor
- Rarity
- Rare
- Uses
- Collector
- Host rock
- In pegmatites in nepheline syenites in differentiated alkalic massifs (Kola Peninsula, Russia); in sodalite xenoliths associated with an intrusive alkalic gabbro-syenite complex (Mont Saint-Hilaire, Canada)
Where rockhounds find natrosilite
Classic worldwide localities
- Mt. Karnasurt, Lovozero massif, and in the Khibiny massif, Kola Peninsula, Russia
- Mont Saint-Hilaire, Quebec, Canada
Field-hunting tip
Where it forms: In pegmatites in nepheline syenites in differentiated alkalic massifs (Kola Peninsula, Russia); in sodalite xenoliths associated with an intrusive alkalic gabbro-syenite complex (Mont Saint-Hilaire, Canada). If you start seeing microcline, analcime, natrolite in float, you are in the right ground. Typical habit: prismatic crystals, massive. Train your eye for that shape before scanning the outcrop.
Common questions
How do you identify natrosilite?+
Where is natrosilite found?+
What rocks look like natrosilite?+
What minerals are found with natrosilite?+
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What is natrosilite used for?+
Find natrosilite on the map
RockHoundR shows mapped rockhounding spots, access rules, and lets you log every find.
