Gatumbaite is a rare phosphate mineral typically found as delicate, radiating clusters of acicular crystals within phosphate-rich pegmatites. It was first identified in the Gatumba pegmatite field of Rwanda and remains a highly sought-after specimen for advanced phosphate mineral collectors.
Is this gatumbaite?
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 gatumbaite with a known reference. Gatumbaite sits at Mohs 3.5, softer than the next harder reference, harder than the previous one.
- 2Check the streakDrag the specimen across an unglazed porcelain plate. Gatumbaite leaves a white streak.
- 3Read the lusterHold the specimen under a strong light. Gatumbaite typically shows a vitreous luster.
- 4Match the color rangeCompare against the expected color range: white, colorless.
- 5Look at form & habitCrystal system: monoclinic. Typical habit: acicular or radiating clusters of prismatic crystals.
Often confused with
Gatumbaite vs. its common look-alikes, and how to tell them apart in the field.
Often found alongside gatumbaite
Minerals reported to co-occur with gatumbaite. Spotting these in float or country rock is a strong cue you are in the right ground.
All properties
- Chemical formula
- CaAl₂(PO₄)₂(OH)₂·H₂O
- Mohs hardness
- 3.5
- Density
- 2.44 g/cm³
- Streak
- White
- Luster
- Vitreous
- Transparency
- Transparent
- Crystal system
- Monoclinic
- Crystal habit
- Acicular or Radiating Clusters of Prismatic Crystals
- Cleavage
- Perfect in One Direction
- Rarity
- Rare
- Uses
- Collector
- Host rock
- Granite Pegmatites
- Typical price
- $50-300 per specimen
Where rockhounds find gatumbaite
Classic worldwide localities
- Gatumba district, Rwanda
- Sapucaia pegmatite, Brazil
Field-hunting tip
Look in granite pegmatites country, the host setting where gatumbaite typically forms. If you start seeing beryllonite, amblygonite, apatite in float, you are in the right ground. Field specimens usually show a acicular or radiating clusters of prismatic crystals habit, so train your eye for that shape before scanning the outcrop.
Common questions
How do you identify gatumbaite?+
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How much is gatumbaite worth?+
What rocks look like gatumbaite?+
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Find gatumbaite on the map
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