Cattiite is an extremely rare magnesium phosphate mineral found primarily in unique phosphate-rich environments like the Big Fish River area. Collectors often find it as small, colorless to white tabular crystals that are highly prone to dehydration, requiring careful storage to prevent degradation. Due to its solubility and fragility, it is considered a specialty mineral primarily for advanced systematic collectors.
Is this cattiite?
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 cattiite with a known reference. Cattiite sits at Mohs 2 — softer than the next harder reference, harder than the previous one.
- 2Check the streakDrag the specimen across an unglazed porcelain plate. Cattiite leaves a white streak.
- 3Read the lusterHold the specimen under a strong light. Cattiite typically shows a vitreous luster.
- 4Match the color rangeCompare against the expected color range: colorless, white.
- 5Look at form & habitCrystal system: triclinic. Typical habit: tabular crystals.
Often confused with
Cattiite vs. its common look-alikes — and how to tell them apart in the field.
Often found alongside cattiite
Minerals reported to co-occur with cattiite. Spotting these in float or country rock is a strong cue you are in the right ground.
All properties
- Chemical formula
- Mg₃(PO₄)₂·22H₂O
- Mohs hardness
- 2
- Density
- 1.79 g/cm³
- Streak
- White
- Luster
- Vitreous
- Transparency
- Transparent
- Crystal system
- Triclinic
- Crystal habit
- Tabular Crystals
- Cleavage
- Perfect
- Rarity
- Rare
- Uses
- Collector
- Host rock
- Phosphate-rich Sedimentary Deposits
- Typical price
- $50-300 per specimen
Where rockhounds find cattiite
Classic worldwide localities
- Big Fish River, Yukon Territory, Canada
Field-hunting tip
Look in phosphate-rich sedimentary deposits country — that is the host setting where cattiite typically forms. If you start seeing struvite, vivianite in float, you are in the right ground. Field specimens usually show a tabular crystals habit, so train your eye for that shape before scanning the outcrop.
Common questions
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Find cattiite on the map
RockHoundR shows mapped rockhounding spots, access rules, and lets you log every find.
