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, 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.
