Pachnolite is a rare fluoride mineral that typically forms as small, colorless, prismatic crystals in late-stage pegmatites. It is most famously associated with the cryolite deposit at Ivigtut, Greenland, where it often appears as a secondary mineral coating other species.
Is this pachnolite?
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 pachnolite with a known reference. Pachnolite 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. Pachnolite leaves a white streak.
- 3Read the lusterHold the specimen under a strong light. Pachnolite typically shows a vitreous luster.
- 4Match the color rangeCompare against the expected color range: colorless, white, grayish.
- 5Look at form & habitCrystal system: monoclinic. Typical habit: prismatic to tabular crystals often in radiating groups.
Often confused with
Pachnolite vs. its common look-alikes — and how to tell them apart in the field.
Often found alongside pachnolite
Minerals reported to co-occur with pachnolite. Spotting these in float or country rock is a strong cue you are in the right ground.
All properties
- Chemical formula
- NaCaAlF₆·H₂O
- Mohs hardness
- 3
- Density
- 2.98 g/cm³
- Streak
- White
- Luster
- Vitreous
- Transparency
- Transparent
- Crystal system
- Monoclinic
- Crystal habit
- Prismatic to Tabular Crystals Often in Radiating Groups
- Cleavage
- Poor
- Rarity
- Uncommon
- Uses
- Collector
- Host rock
- Cryolite-bearing Pegmatites
- Typical price
- $20-150 thumbnail specimens
Where rockhounds find pachnolite
Classic worldwide localities
- Ivigtut, Greenland
- Pikes Peak, Colorado, USA
- Aragats, Armenia
Field-hunting tip
Look in cryolite-bearing pegmatites country — that is the host setting where pachnolite typically forms. If you start seeing thomsenolite, cryolite, siderite in float, you are in the right ground. Field specimens usually show a prismatic to tabular crystals often in radiating groups habit, so train your eye for that shape before scanning the outcrop.
Common questions
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Find pachnolite on the map
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