Stercorite is a rare phosphate mineral found primarily in guano deposits where bird or bat droppings have reacted with underlying sediments. It typically forms as small, tabular, colorless to white crystals or crusts and is highly susceptible to dehydration when exposed to air.
Is this stercorite?
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 stercorite with a known reference. Stercorite 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. Streak: white.
- 3Read the lusterHold the specimen under a strong light. Luster: vitreous.
- 4Match the color rangeCompare against the expected color range: white, colorless, yellowish, brownish.
- 5Look at form & habitCrystal system: triclinic. Typical habit: tabular crystals, crusts, granular.
Often confused with
Stercorite vs. its common look-alikes, and how to tell them apart in the field.
Often found alongside stercorite
Minerals reported to co-occur with stercorite. Spotting these in float or country rock is a strong cue you are in the right ground.
All properties
- Chemical formula
- NaNH₄HPO₄·4H₂O
- Mohs hardness
- 2
- Density
- 1.574 g/cm³
- Streak
- White
- Luster
- Vitreous
- Transparency
- Transparent
- Crystal system
- Triclinic
- Crystal habit
- Tabular crystals, crusts, granular
- Cleavage
- None
- Rarity
- Rare
- Uses
- Collector, Scientific research
- Host rock
- In bird and bat guano deposits
Where rockhounds find stercorite
Classic worldwide localities
- Ichaboe Island, northwest of Lüderitz, Namibia
- Guañape Island, south of Trujillo, Peru
- Petrogale Cave, near Madura, Western Australia
Field-hunting tip
Where it forms: In bird and bat guano deposits. If you start seeing struvite, archerite, biphosphammite in float, you are in the right ground. Typical habit: tabular crystals, crusts, granular. Train your eye for that shape before scanning the outcrop.
Common questions
How do you identify stercorite?+
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What rocks look like stercorite?+
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Find stercorite on the map
RockHoundR shows mapped rockhounding spots, access rules, and lets you log every find.
