Phosphammite is a rare ammonium phosphate mineral that typically forms as a secondary mineral in guano deposits. It is highly soluble and hygroscopic, meaning it should be stored in a dry, sealed container to prevent deliquescence.
Is this phosphammite?
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 phosphammite with a known reference. Phosphammite sits at Mohs 1.5-2, softer than the next harder reference, harder than the previous one.
- 2Check the streakDrag the specimen across an unglazed porcelain plate. Phosphammite leaves a white streak.
- 3Read the lusterHold the specimen under a strong light. Phosphammite typically shows a vitreous luster.
- 4Match the color rangeCompare against the expected color range: white, colorless, yellowish.
- 5Look at form & habitCrystal system: monoclinic. Typical habit: crusts, granular, powdery aggregates.
Often confused with
Phosphammite vs. its common look-alikes, and how to tell them apart in the field.
Often found alongside phosphammite
Minerals reported to co-occur with phosphammite. Spotting these in float or country rock is a strong cue you are in the right ground.
All properties
- Chemical formula
- (NH₄)₂HPO₄
- Mohs hardness
- 1.5-2
- Density
- 1.84 g/cm³
- Streak
- White
- Luster
- Vitreous
- Transparency
- Transparent
- Crystal system
- Monoclinic
- Crystal habit
- Crusts, Granular, Powdery Aggregates
- Cleavage
- Perfect
- Rarity
- Rare
- Uses
- Collector
- Host rock
- Guano Deposits in Arid Caves or Island Environments
- Typical price
- $20-100 for small specimens
Where rockhounds find phosphammite
Classic worldwide localities
- Guaiave Island (Venezuela)
- Chincha Islands (Peru)
- various guano deposits
Field-hunting tip
Look in guano deposits in arid caves or island environments country, the host setting where phosphammite typically forms. If you start seeing mascagnite, boussingaultite, taranakite in float, you are in the right ground. Field specimens usually show a crusts, granular, powdery aggregates habit, so train your eye for that shape before scanning the outcrop.
Common questions
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Find phosphammite on the map
RockHoundR shows mapped rockhounding spots, access rules, and lets you log every find.
