Spheniscidite is a rare phosphate mineral typically found as secondary crusts or fine platy crystals in guano-rich environments. Collectors usually find it as white to yellow earthy aggregates associated with other phosphate minerals in oceanic island deposits.
Is this spheniscidite?
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 spheniscidite with a known reference. Spheniscidite 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. Spheniscidite leaves a white streak.
- 3Read the lusterHold the specimen under a strong light. Spheniscidite typically shows a pearly luster.
- 4Match the color rangeCompare against the expected color range: yellow, yellowish-brown, white.
- 5Look at form & habitCrystal system: monoclinic. Typical habit: platy crystals, crusts, pulverulent.
Often confused with
Spheniscidite vs. its common look-alikes — and how to tell them apart in the field.
Often found alongside spheniscidite
Minerals reported to co-occur with spheniscidite. Spotting these in float or country rock is a strong cue you are in the right ground.
All properties
- Chemical formula
- (NH₄)(Fe³⁺,Al)₂(PO₄)₂(OH)·2H₂O
- Mohs hardness
- 2
- Density
- 2.12 g/cm³
- Streak
- White
- Luster
- Pearly
- Transparency
- Translucent
- Crystal system
- Monoclinic
- Crystal habit
- Platy Crystals, Crusts, Pulverulent
- Cleavage
- Perfect On {001}
- Rarity
- Rare
- Uses
- Collector
- Host rock
- Guano Deposits On Island Rocks
- Typical price
- $50-300 per specimen
Where rockhounds find spheniscidite
Classic worldwide localities
- Penguin Island, South Africa
- Ichaboe Island, Namibia
- Guano islands, various
Field-hunting tip
Look in guano deposits on island rocks country — that is the host setting where spheniscidite typically forms. If you start seeing leucophosphite, taranakite, ammonia-stromeyerite in float, you are in the right ground. Field specimens usually show a platy crystals, crusts, pulverulent habit, so train your eye for that shape before scanning the outcrop.
Common questions
How do you identify spheniscidite?+
Where is spheniscidite found?+
How much is spheniscidite worth?+
What rocks look like spheniscidite?+
What minerals are found with spheniscidite?+
What kind of rock does spheniscidite form in?+
What is spheniscidite used for?+
Find spheniscidite on the map
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