Kingsmountite is a rare phosphate mineral primarily known from the iron-rich sedimentary deposits of the Yukon. It typically forms delicate, needle-like acicular crystals or radiating sprays that are highly sought after by mineral collectors for their aesthetic crystallization.
Is this kingsmountite?
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 kingsmountite with a known reference. Kingsmountite 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. Kingsmountite leaves a white streak.
- 3Read the lusterHold the specimen under a strong light. Kingsmountite 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: acicular crystals, radiating sprays, compact masses.
Often confused with
Kingsmountite vs. its common look-alikes — and how to tell them apart in the field.
Often found alongside kingsmountite
Minerals reported to co-occur with kingsmountite. Spotting these in float or country rock is a strong cue you are in the right ground.
All properties
- Chemical formula
- Ca₄Al₂[PO₄]₂(OH)₈·5H₂O
- Mohs hardness
- 3-4
- Density
- 2.16 g/cm³
- Streak
- White
- Luster
- Vitreous
- Transparency
- Transparent
- Crystal system
- Monoclinic
- Crystal habit
- Acicular Crystals, Radiating Sprays, Compact Masses
- Cleavage
- Perfect in One Direction
- Rarity
- Rare
- Uses
- Collector
- Host rock
- Sedimentary Iron-formation
- Typical price
- $50-300 per specimen
Where rockhounds find kingsmountite
Classic worldwide localities
- Big Fish River, Yukon Territory, Canada
- Rapid Creek, Yukon Territory, Canada
Field-hunting tip
Look in sedimentary iron-formation country — that is the host setting where kingsmountite typically forms. If you start seeing lazulite, siderite, quartz in float, you are in the right ground. Field specimens usually show a acicular crystals, radiating sprays, compact masses habit, so train your eye for that shape before scanning the outcrop.
Common questions
How do you identify kingsmountite?+
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Find kingsmountite on the map
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