Leucophosphite is a rare hydrated potassium iron phosphate mineral that typically forms as a secondary mineral in phosphate-rich pegmatites. It is often found as small, platy, or chalky coatings and aggregates, frequently appearing in shades of white to yellowish-brown. Collectors generally look for it in associations with other iron-phosphate minerals like rockbridgeite and triphylite.
Is this leucophosphite?
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 leucophosphite with a known reference. Leucophosphite sits at Mohs 3.5, 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 to waxy, chalky.
- 4Match the color rangeCompare against the expected color range: white, brown, brownish yellow, colorless, greenish.
- 5Look at form & habitCrystal system: monoclinic. Typical habit: platy crystals, granular aggregates, coatings.
Often confused with
Leucophosphite vs. its common look-alikes, and how to tell them apart in the field.
Often found alongside leucophosphite
Minerals reported to co-occur with leucophosphite. Spotting these in float or country rock is a strong cue you are in the right ground.
All properties
- Chemical formula
- KFe₂³⁺(PO₄)₂(OH)·2H₂O
- Mohs hardness
- 3.5
- Density
- 2.948 g/cm³
- Streak
- White
- Luster
- Vitreous to waxy, chalky
- Transparency
- Semitransparent
- Crystal system
- Monoclinic
- Crystal habit
- Platy crystals, granular aggregates, coatings
- Cleavage
- {100}, perfect
- Rarity
- Rare
- Uses
- Collector
- Host rock
- Formed by reaction between bat or bird guano and earlier iron-bearing minerals; by hydrothermal alteration of iron-rich phosphates in complex granite pegmatites; crosscutting fluorapatite nodules in black shale
Where rockhounds find leucophosphite
Classic worldwide localities
- Palermo #1 mine, near North Groton, Grafton Co., New Hampshire, USA
- Bethel Church, Pike Co., Indiana, USA
- Tip Top pegmatite, 8.5 km southwest of Custer, also at the Gap Lode, White Elephant, and Bull Moose mines, near Custer, Custer Co., South Dakota, USA
- Ninghanboun Hills, on the shore of Weelhamby Lake, Western Australia
- Moculta phosphate quarry, northeast of Angaston, and at the Fairview quarry, near Robertstown, South Australia
- Bomi Hill, Bambuta, and other caves, Liberia
Field-hunting tip
Where it forms: Formed by reaction between bat or bird guano and earlier iron-bearing minerals; by hydrothermal alteration of iron-rich phosphates in complex granite pegmatites; crosscutting fluorapatite nodules in black shale. If you start seeing variscite, chalcedony, opal in float, you are in the right ground. Typical habit: platy crystals, granular aggregates, coatings. Train your eye for that shape before scanning the outcrop.
Common questions
How do you identify leucophosphite?+
Where is leucophosphite found?+
What rocks look like leucophosphite?+
What minerals are found with leucophosphite?+
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Find leucophosphite on the map
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