Fluellite is a rare phosphate mineral typically found as small, sharp, colorless pyramidal crystals. It is most frequently collected from granite pegmatites and associated phosphate-rich hydrothermal deposits where it occurs as a secondary mineral.
Is this fluellite?
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 fluellite with a known reference. Fluellite 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. Streak: white.
- 3Read the lusterHold the specimen under a strong light. Luster: vitreous.
- 4Match the color rangeCompare against the expected color range: colorless, golden yellow, dark purple, black.
- 5Look at form & habitCrystal system: orthorhombic. Typical habit: pyramidal crystals, prismatic crystals.
Often confused with
Fluellite vs. its common look-alikes, and how to tell them apart in the field.
Often found alongside fluellite
Minerals reported to co-occur with fluellite. Spotting these in float or country rock is a strong cue you are in the right ground.
All properties
- Chemical formula
- Al₂PO₄F₂OH·7H₂O
- Mohs hardness
- 3
- Density
- 2.14-2.18 g/cm³
- Colors
- Streak
- White
- Luster
- Vitreous
- Transparency
- Transparent
- Crystal system
- Orthorhombic
- Crystal habit
- Pyramidal crystals, prismatic crystals
- Cleavage
- On {001} and {111}, both indistinct
- Fluorescence
- Creamy white under LW UV
- Rarity
- Rare
- Uses
- Collector
- Host rock
- A rare secondary mineral, formed by weathering of earlier phosphates in some complex granite pegmatites
Where rockhounds find fluellite
Classic worldwide localities
- Carolina pyrophyllite mine, Staley, Randolph Co., North Carolina, USA
- Gold Quarry mine, near Carlin, Maggie Creek district, Eureka Co., and at the Silver Coin mine, near Valmy, Iron Point district, Humboldt Co., Nevada, USA
- Tuscarora mine, near Randolph, Rich Co., Utah, USA
- Cornwall, from the Stenna Gwynn mine, St. Stephen-in-Brannel, and at the Goonvean china clay pit, St. Austell, England
- Bavaria, on the Kreuzberg, Pleystein, and as Hagendorf, Germany
- Lázně Kynzvart, near Mariánské Lázně (Königswart, near Marienbad), Czech Republic
Field-hunting tip
Where it forms: A rare secondary mineral, formed by weathering of earlier phosphates in some complex granite pegmatites. If you start seeing fluorapatite, wavellite, phosphosiderite in float, you are in the right ground. Typical habit: pyramidal crystals, prismatic crystals. Train your eye for that shape before scanning the outcrop.
Common questions
How do you identify fluellite?+
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What rocks look like fluellite?+
What minerals are found with fluellite?+
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Find fluellite on the map
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