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. Stercorite leaves a white streak.
- 3Read the lusterHold the specimen under a strong light. Stercorite typically shows a vitreous luster.
- 4Match the color rangeCompare against the expected color range: white, colorless.
- 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
- 1.61 g/cm³
- Streak
- White
- Luster
- Vitreous
- Transparency
- Transparent
- Crystal system
- Triclinic
- Crystal habit
- Tabular Crystals, Crusts, Granular
- Cleavage
- Good
- Rarity
- Rare
- Uses
- Collector, Scientific Research
- Host rock
- Guano Deposits
- Typical price
- $20-100 for small study specimens
Where rockhounds find stercorite
Classic worldwide localities
- Guano Islands, Peru
- Mon Island, Denmark
- various guano deposits
Field-hunting tip
Look in guano deposits country — that is the host setting where stercorite typically forms. If you start seeing struvite, newberyite, brushite in float, you are in the right ground. Field specimens usually show a tabular crystals, crusts, granular habit, so train your eye for that shape before scanning the outcrop.
Common questions
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Find stercorite on the map
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