Oxammite is an extremely rare organic mineral found primarily in guano deposits on islands where it forms through the reaction of bird excrement with phosphate-rich environments. It typically appears as white, crumbly crusts or small crystalline efflorescences that are highly susceptible to dissolution in water or humidity.
Is this oxammite?
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 oxammite with a known reference. Oxammite sits at Mohs 2.5, softer than the next harder reference, harder than the previous one.
- 2Check the streakDrag the specimen across an unglazed porcelain plate. Oxammite leaves a white streak.
- 3Read the lusterHold the specimen under a strong light. Oxammite typically shows a vitreous luster.
- 4Match the color rangeCompare against the expected color range: white, colorless.
- 5Look at form & habitCrystal system: orthorhombic. Typical habit: crusts, efflorescences, or tiny granular aggregates.
Often confused with
Oxammite vs. its common look-alikes, and how to tell them apart in the field.
Often found alongside oxammite
Minerals reported to co-occur with oxammite. Spotting these in float or country rock is a strong cue you are in the right ground.
All properties
- Chemical formula
- (NH₄)₂C₂O₄·H₂O
- Mohs hardness
- 2.5
- Density
- 1.78 g/cm³
- Streak
- White
- Luster
- Vitreous
- Transparency
- Transparent
- Crystal system
- Orthorhombic
- Crystal habit
- Crusts, Efflorescences, Or Tiny Granular Aggregates
- Cleavage
- Distinct
- Rarity
- Rare
- Uses
- Collector
- Host rock
- Guano Deposits
- Typical price
- $50-300 per specimen
Where rockhounds find oxammite
Classic worldwide localities
- Guañape Islands, Peru
- Ichaboe Island, Namibia
Field-hunting tip
Look in guano deposits country, the host setting where oxammite typically forms. If you start seeing guanine, struvite, phosphammite in float, you are in the right ground. Field specimens usually show a crusts, efflorescences, or tiny granular aggregates habit, so train your eye for that shape before scanning the outcrop.
Common questions
How do you identify oxammite?+
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What rocks look like oxammite?+
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Find oxammite on the map
RockHoundR shows mapped rockhounding spots, access rules, and lets you log every find.
