Galliskiite is an extremely rare phosphate mineral discovered in complex granite pegmatites. It typically forms as small, colorless to white tabular crystals and is primarily sought after by advanced systematic mineral collectors.
Is this galliskiite?
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 galliskiite with a known reference. Galliskiite sits at Mohs 2.5, 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.
- 5Look at form & habitCrystal system: triclinic. Typical habit: tabular crystals.
Often confused with
Galliskiite vs. its common look-alikes, and how to tell them apart in the field.
Often found alongside galliskiite
Minerals reported to co-occur with galliskiite. Spotting these in float or country rock is a strong cue you are in the right ground.
All properties
- Chemical formula
- Ca₄Al₂F₈(PO₄)₂·5H₂O
- Mohs hardness
- 2.5
- Density
- 2.67 g/cm³
- Colors
- Streak
- White
- Luster
- Vitreous
- Transparency
- Transparent
- Crystal system
- Triclinic
- Crystal habit
- Tabular crystals
- Cleavage
- Two fair at ~90°, probably {010} and {001}
- Rarity
- Rare
- Uses
- Collector
- Host rock
- A late-stage hydrothermal mineral that crystallized from fluorine-rich solutions in intragranitic pegmatite
Where rockhounds find galliskiite
Classic worldwide localities
- Gigante pegmatite, 18.45 km west-southwest of Tanti, Punilla department, Córdoba Province, Argentina
Field-hunting tip
Where it forms: A late-stage hydrothermal mineral that crystallized from fluorine-rich solutions in intragranitic pegmatite. If you start seeing morinite, strengite in float, you are in the right ground. Typical habit: tabular crystals. Train your eye for that shape before scanning the outcrop.
Common questions
How do you identify galliskiite?+
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What rocks look like galliskiite?+
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Find galliskiite on the map
RockHoundR shows mapped rockhounding spots, access rules, and lets you log every find.
