Struvite is a phosphate mineral commonly found in bat guano deposits and human environments like sewage pipes. It forms distinct, orthorhombic crystals that are usually transparent to translucent, but the mineral is prone to dehydration when exposed to air.
Is this struvite?
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 struvite with a known reference. Struvite 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, yellowish white, brownish white.
- 5Look at form & habitCrystal system: orthorhombic. Typical habit: euhedral crystals, platy.
Often confused with
Struvite vs. its common look-alikes, and how to tell them apart in the field.
Often found alongside struvite
Minerals reported to co-occur with struvite. Spotting these in float or country rock is a strong cue you are in the right ground.
All properties
- Chemical formula
- NH₄MgPO₄·6H₂O
- Mohs hardness
- 2
- Density
- 1.711 g/cm³
- Streak
- White
- Luster
- Vitreous
- Transparency
- Transparent to translucent
- Crystal system
- Orthorhombic
- Crystal habit
- Euhedral crystals, platy
- Cleavage
- {001}, good; {010}, poor
- Rarity
- Common
- Uses
- Collector, Scientific research
- Host rock
- In peaty earth intermixed with cattle dung (Hamburg, Germany); typically formed in bird or bat guano in caves and surface deposits
Where rockhounds find struvite
Classic worldwide localities
- Paoha Island, Mono Lake, Mono Co., California, USA
- Found under St. Nikolai Church, Hamburg, Germany
- An archaeological excavation at High Street and Fishamble Street, Dublin, Ireland
- Limfjord, Denmark
- Niah Great Cave, Sarawak, Malaysia
- Saldanha Bay, Cape Province, and Ficus and Boon’s Caves, Transvaal, South Africa
Field-hunting tip
Where it forms: In peaty earth intermixed with cattle dung (Hamburg, Germany); typically formed in bird or bat guano in caves and surface deposits. If you start seeing newberyite, hannayite, brushite in float, you are in the right ground. Typical habit: euhedral crystals, platy. Train your eye for that shape before scanning the outcrop.
Common questions
How do you identify struvite?+
Where is struvite found?+
What rocks look like struvite?+
What minerals are found with struvite?+
What kind of rock does struvite form in?+
What is struvite used for?+
Find struvite on the map
RockHoundR shows mapped rockhounding spots, access rules, and lets you log every find.
