Afmite is a rare aluminum phosphate mineral typically found as small, thin platy crystals or delicate radial sprays. It is primarily known from the Kobokobo pegmatite in the Democratic Republic of the Congo, often associated with other rare phosphate species. Due to its scarcity and fragile nature, it is a highly sought-after specimen for advanced mineral collectors.
Is this afmite?
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 afmite with a known reference. Afmite sits at Mohs ~1.5, 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: pearly; dull on weathered surfaces.
- 4Match the color rangeCompare against the expected color range: colorless, white.
- 5Look at form & habitCrystal system: triclinic. Typical habit: platy crystals, radial aggregates.
Often confused with
Afmite vs. its common look-alikes, and how to tell them apart in the field.
How to tell apart: Vauxite is the harder of the two (Mohs 3.5 vs. ~1.5); luster reads pearly; dull on weathered surfaces on Afmite and vitreous on Vauxite.
How to tell apart: Paravauxite is the harder of the two (Mohs 3 vs. ~1.5); luster reads pearly; dull on weathered surfaces on Afmite and vitreous, pearly on cleavages on Paravauxite.
Often found alongside afmite
Minerals reported to co-occur with afmite. Spotting these in float or country rock is a strong cue you are in the right ground.
All properties
- Chemical formula
- Al₃(OH)₄(H₂O)₃(PO₄)(PO₃OH)·H₂O
- Mohs hardness
- ~1.5
- Density
- 2.39 g/cm³
- Streak
- White
- Luster
- Pearly; dull on weathered surfaces
- Transparency
- Transparent
- Crystal system
- Triclinic
- Crystal habit
- Platy crystals, radial aggregates
- Cleavage
- Perfect on {001}, good on {010} and {11̄0}
- Rarity
- Rare
- Uses
- Collector
- Host rock
- A secondary mineral formed by remobilization and crystallization during low-temperature hydrothermal activity and/or weathering and ground water activity
Where rockhounds find afmite
Classic worldwide localities
- Bachman mine, Hellertown, Pennsylvania, USA
- Fumade, Castelnau-de-Brassac, Tarn, France
- Kobokobo pegmatite, Democratic Republic of Congo
Field-hunting tip
Where it forms: A secondary mineral formed by remobilization and crystallization during low-temperature hydrothermal activity and/or weathering and ground water activity. If you start seeing matulaite, variscite, kobokoboite in float, you are in the right ground. Typical habit: platy crystals, radial aggregates. Train your eye for that shape before scanning the outcrop.
Common questions
How do you identify afmite?+
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What rocks look like afmite?+
What minerals are found with afmite?+
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Find afmite on the map
RockHoundR shows mapped rockhounding spots, access rules, and lets you log every find.
