Penikisite is a rare barium-magnesium phosphate mineral that occurs as small, delicate crystals. It is most famously found in the phosphate-rich concretions of the Big Fish River and Rapid Creek regions in Yukon, Canada, often associated with other rare phosphate species.
Is this penikisite?
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 penikisite with a known reference. Penikisite sits at Mohs 4 — softer than the next harder reference, harder than the previous one.
- 2Check the streakDrag the specimen across an unglazed porcelain plate. Penikisite leaves a white streak.
- 3Read the lusterHold the specimen under a strong light. Penikisite typically shows a vitreous luster.
- 4Match the color rangeCompare against the expected color range: white, colorless, pale yellow.
- 5Look at form & habitCrystal system: monoclinic. Typical habit: tabular to equant crystals, often in radial aggregates.
Often confused with
Penikisite vs. its common look-alikes — and how to tell them apart in the field.
Often found alongside penikisite
Minerals reported to co-occur with penikisite. Spotting these in float or country rock is a strong cue you are in the right ground.
All properties
- Chemical formula
- BaMg₂(AlPO₄)₂(OH)₂
- Mohs hardness
- 4
- Density
- 3.31 g/cm³
- Streak
- White
- Luster
- Vitreous
- Transparency
- Transparent
- Crystal system
- Monoclinic
- Crystal habit
- Tabular to Equant Crystals, Often in Radial Aggregates
- Cleavage
- None
- Rarity
- Rare
- Uses
- Collector
- Host rock
- Phosphate-rich Sedimentary Concretions in Iron-formation
- Typical price
- $50-300 per specimen
Where rockhounds find penikisite
Classic worldwide localities
- Big Fish River, Yukon, Canada
- Rapid Creek, Yukon, Canada
Field-hunting tip
Look in phosphate-rich sedimentary concretions in iron-formation country — that is the host setting where penikisite typically forms. If you start seeing gormanite, ludlamite, vivianite in float, you are in the right ground. Field specimens usually show a tabular to equant crystals, often in radial aggregates habit, so train your eye for that shape before scanning the outcrop.
Common questions
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Find penikisite on the map
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