Tancoite is an exceptionally rare phosphate mineral discovered at the Tanco pegmatite mine. It typically forms as small, transparent to translucent, colorless or pale pink crystals within complex pegmatite zones.
Is this tancoite?
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 tancoite with a known reference. Tancoite sits at Mohs 4-4.5, softer than the next harder reference, harder than the previous one.
- 2Check the streakDrag the specimen across an unglazed porcelain plate. Streak: white.
- 3Read the lusterHold the specimen under a strong light. Luster: vitreous.
- 4Match the color rangeCompare against the expected color range: colorless, light pink.
- 5Look at form & habitCrystal system: orthorhombic. Typical habit: columnar, druse.
Often confused with
Tancoite vs. its common look-alikes, and how to tell them apart in the field.
Often found alongside tancoite
Minerals reported to co-occur with tancoite. Spotting these in float or country rock is a strong cue you are in the right ground.
All properties
- Chemical formula
- Na₂LiHAl(PO₄)₂OH
- Mohs hardness
- 4-4.5
- Density
- 2.752 g/cm³
- Colors
- Streak
- White
- Luster
- Vitreous
- Transparency
- Transparent
- Crystal system
- Orthorhombic
- Crystal habit
- Columnar, druse
- Cleavage
- On {010} and {100}, fair
- Rarity
- Rare
- Uses
- Collector
- Host rock
- In cavities in dump material from a complex granite pegmatite
Where rockhounds find tancoite
Classic worldwide localities
- Tanco mine, Bernic Lake, Manitoba, Canada
Field-hunting tip
Where it forms: In cavities in dump material from a complex granite pegmatite. If you start seeing lithiophosphate, apatite, spodumene in float, you are in the right ground. Typical habit: columnar, druse. Train your eye for that shape before scanning the outcrop.
Common questions
How do you identify tancoite?+
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What rocks look like tancoite?+
What minerals are found with tancoite?+
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Find tancoite on the map
RockHoundR shows mapped rockhounding spots, access rules, and lets you log every find.
