Niter, commonly known as saltpeter, typically forms as delicate, hair-like efflorescences or thin crusts in extremely arid environments such as cave walls or dry soil. It is water-soluble and highly hygroscopic, making it difficult to preserve in humid conditions; collectors should store it in sealed containers.
Is this niter?
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 niter with a known reference. Niter sits at Mohs 2 — softer than the next harder reference, harder than the previous one.
- 2Check the streakDrag the specimen across an unglazed porcelain plate. Niter leaves a white streak.
- 3Read the lusterHold the specimen under a strong light. Niter typically shows a vitreous luster.
- 4Match the color rangeCompare against the expected color range: white, colorless, gray, yellowish.
- 5Look at form & habitCrystal system: orthorhombic. Typical habit: acicular, fibrous, crusts, efflorescences.
Often confused with
Niter vs. its common look-alikes — and how to tell them apart in the field.
Often found alongside niter
Minerals reported to co-occur with niter. Spotting these in float or country rock is a strong cue you are in the right ground.
All properties
- Chemical formula
- KNO₃
- Mohs hardness
- 2
- Density
- 2.1 g/cm³
- Streak
- White
- Luster
- Vitreous
- Transparency
- Transparent
- Crystal system
- Orthorhombic
- Crystal habit
- Acicular, Fibrous, Crusts, Efflorescences
- Cleavage
- Perfect
- Rarity
- Uncommon
- Uses
- Collector, Historical Manufacture of Gunpowder, Fertilizer
- Host rock
- Arid Cave Walls, Soil Crusts, Dry Climate Deposits
- Typical price
- $10-50 per specimen
Where rockhounds find niter
1 mapped spotsClassic worldwide localities
- Chile
- India
- Iran
- Egypt
- United States
Field-hunting tip
Look in arid cave walls, soil crusts, dry climate deposits country — that is the host setting where niter typically forms. If you start seeing nitrocalcite, gypsum, epsomite in float, you are in the right ground. Field specimens usually show a acicular, fibrous, crusts, efflorescences habit, so train your eye for that shape before scanning the outcrop. In the U.S., the densest reported localities are in Utah — start trip planning there.
Common questions
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Find niter on the map
RockHoundR shows mapped rockhounding spots, access rules, and lets you log every find.
