Mcauslanite is an extremely rare phosphate mineral typically found as small, fragile blue to colorless crystals in phosphate-rich environments. It is often discovered as an alteration product within nodules in sedimentary shales and requires careful handling due to its low hardness and delicate crystal structure.
Is this mcauslanite?
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 mcauslanite with a known reference. Mcauslanite 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. Mcauslanite leaves a white streak.
- 3Read the lusterHold the specimen under a strong light. Mcauslanite typically shows a vitreous luster.
- 4Match the color rangeCompare against the expected color range: blue, greenish-blue, colorless.
- 5Look at form & habitCrystal system: triclinic. Typical habit: tabular to prismatic crystals, often as crusts or aggregates.
Often confused with
Mcauslanite vs. its common look-alikes — and how to tell them apart in the field.
Often found alongside mcauslanite
Minerals reported to co-occur with mcauslanite. Spotting these in float or country rock is a strong cue you are in the right ground.
All properties
- Chemical formula
- H₂NaAl₃(PO₄)₂F₂·18H₂O
- Mohs hardness
- 3
- Density
- 2.36 g/cm³
- Streak
- White
- Luster
- Vitreous
- Transparency
- Transparent
- Crystal system
- Triclinic
- Crystal habit
- Tabular to Prismatic Crystals, Often as Crusts or Aggregates
- Cleavage
- Perfect On {001}
- Rarity
- Rare
- Uses
- Collector
- Host rock
- Phosphate-bearing Nodules in Shale
- Typical price
- $50-300 for small high-quality specimens
Where rockhounds find mcauslanite
Classic worldwide localities
- McAuslan Mountain, Quebec, Canada
- Big Fish River, Yukon, Canada
Field-hunting tip
Look in phosphate-bearing nodules in shale country — that is the host setting where mcauslanite typically forms. If you start seeing quartz, siderite, vivianite in float, you are in the right ground. Field specimens usually show a tabular to prismatic crystals, often as crusts or aggregates habit, so train your eye for that shape before scanning the outcrop.
Common questions
How do you identify mcauslanite?+
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How much is mcauslanite worth?+
What rocks look like mcauslanite?+
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Find mcauslanite on the map
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