Paulkerrite is a rare phosphate mineral typically found as delicate, pale yellow to brownish-tan platy crystals. It most commonly occurs within phosphate-rich zones of granitic pegmatites, often forming radial or sheaf-like aggregates. Due to its scarcity and fragile habit, it is primarily a target for specialized mineral collectors.
Is this paulkerrite?
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 paulkerrite with a known reference. Paulkerrite sits at Mohs 3-4 — softer than the next harder reference, harder than the previous one.
- 2Check the streakDrag the specimen across an unglazed porcelain plate. Paulkerrite leaves a white streak.
- 3Read the lusterHold the specimen under a strong light. Paulkerrite typically shows a vitreous luster.
- 4Match the color rangeCompare against the expected color range: yellow, yellow-brown, tan.
- 5Look at form & habitCrystal system: monoclinic. Typical habit: platy crystals, radial aggregates.
Often confused with
Paulkerrite vs. its common look-alikes — and how to tell them apart in the field.
Often found alongside paulkerrite
Minerals reported to co-occur with paulkerrite. Spotting these in float or country rock is a strong cue you are in the right ground.
All properties
- Chemical formula
- KMgAl₂(PO₄)₂(OH)₂·8H₂O
- Mohs hardness
- 3-4
- Density
- 2.81 g/cm³
- Colors
- Streak
- White
- Luster
- Vitreous
- Transparency
- Transparent
- Crystal system
- Monoclinic
- Crystal habit
- Platy Crystals, Radial Aggregates
- Cleavage
- Perfect On {001}
- Rarity
- Rare
- Uses
- Collector
- Host rock
- Granite Pegmatites
- Typical price
- $50-300 per specimen
Where rockhounds find paulkerrite
Classic worldwide localities
- Tip Top Mine, South Dakota, USA
- Bull Moose Mine, South Dakota, USA
Field-hunting tip
Look in granite pegmatites country — that is the host setting where paulkerrite typically forms. If you start seeing quartz, muscovite, albite in float, you are in the right ground. Field specimens usually show a platy crystals, radial aggregates habit, so train your eye for that shape before scanning the outcrop.
Common questions
How do you identify paulkerrite?+
Where is paulkerrite found?+
How much is paulkerrite worth?+
What rocks look like paulkerrite?+
What minerals are found with paulkerrite?+
What kind of rock does paulkerrite form in?+
What is paulkerrite used for?+
Find paulkerrite on the map
RockHoundR shows mapped rockhounding spots, access rules, and lets you log every find.
