Iangreyite is a very rare aluminum phosphate mineral typically found as small, thin, pearly white plates or crusts. It is most commonly identified in phosphate-rich mineral assemblages, requiring professional chemical analysis for positive identification due to its similarity to other rare phosphates.
Is this iangreyite?
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 iangreyite with a known reference. Iangreyite sits at Mohs 3, 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, pearly (aggregates).
- 4Match the color rangeCompare against the expected color range: white, colorless, cream, yellowish.
- 5Look at form & habitCrystal system: trigonal. Typical habit: platy crystals, crusts, aggregates.
Often confused with
Iangreyite vs. its common look-alikes, and how to tell them apart in the field.
Often found alongside iangreyite
Minerals reported to co-occur with iangreyite. Spotting these in float or country rock is a strong cue you are in the right ground.
All properties
- Chemical formula
- Ca₂Al₇(PO₄)₂(PO₃OH)₂(OH,F)₁₅·8H₂O
- Mohs hardness
- 3
- Density
- 2.46 g/cm³
- Streak
- White
- Luster
- Vitreous, pearly (aggregates)
- Transparency
- Transparent to translucent
- Crystal system
- Trigonal
- Crystal habit
- Platy crystals, crusts, aggregates
- Cleavage
- Perfect, {001}
- Rarity
- Rare
- Uses
- Collector
- Host rock
- phosphate-rich pegmatites and hydrothermal veins
Where rockhounds find iangreyite
Classic worldwide localities
- Silver Coin mine, Valmy, Iron Point district, Humboldt County, Nevada, USA, Czech Republic
Field-hunting tip
Where it forms: phosphate-rich pegmatites and hydrothermal veins. If you start seeing meurigite-na, plumbogummite, kidwellite in float, you are in the right ground. Typical habit: platy crystals, crusts, aggregates. Train your eye for that shape before scanning the outcrop.
Common questions
How do you identify iangreyite?+
Where is iangreyite found?+
What rocks look like iangreyite?+
What minerals are found with iangreyite?+
What kind of rock does iangreyite form in?+
What is iangreyite used for?+
Find iangreyite on the map
RockHoundR shows mapped rockhounding spots, access rules, and lets you log every find.
