Karibibite is a rare secondary mineral found in the oxidation zones of arsenic-rich ore deposits. It typically forms delicate, yellow, needle-like or fibrous sprays that are highly fragile and prized by micromount collectors.
Is this karibibite?
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 karibibite with a known reference. Karibibite sits at Mohs 1-2, softer than the next harder reference, harder than the previous one.
- 2Check the streakDrag the specimen across an unglazed porcelain plate. Streak: bright yellow.
- 3Read the lusterHold the specimen under a strong light. Luster: resinous.
- 4Match the color rangeCompare against the expected color range: brownish yellow.
- 5Look at form & habitCrystal system: orthorhombic. Typical habit: fibrous.
Often confused with
Karibibite vs. its common look-alikes, and how to tell them apart in the field.
How to tell apart: Streak differs, so Karibibite leaves bright yellow, Pharmacosiderite leaves yellowish green; luster reads resinous on Karibibite and adamantine to greasy on Pharmacosiderite.
How to tell apart: Scorodite is the harder of the two (Mohs 3.5-4 vs. 1-2); streak differs, so Karibibite leaves bright yellow, Scorodite leaves greenish white; luster reads resinous on Karibibite and vitreous to subadamantine, subresinous on Scorodite.
Often found alongside karibibite
Minerals reported to co-occur with karibibite. Spotting these in float or country rock is a strong cue you are in the right ground.
All properties
- Chemical formula
- Fe₃(AsO₂)₄(As₂O₅)(OH)
- Mohs hardness
- 1-2
- Density
- 4.07 g/cm³
- Colors
- Streak
- Bright yellow
- Luster
- Resinous
- Transparency
- Transparent
- Crystal system
- Orthorhombic
- Crystal habit
- Fibrous
- Cleavage
- Possibly on {100} or {010}, as indicated by preferred orientation of fibers
- Fluorescence
- Yellow under SW UV
- Rarity
- Rare
- Uses
- Collector
- Host rock
- In granite pegmatites
Where rockhounds find karibibite
Classic worldwide localities
- Rubicon pegmatite, and perhaps others, in the Karibib district, Namibia
- Kiura mine, Oita Prefecture, Japan
- Bou Azzer, Morocco
- Córrego do Urucum pegmatite, near Galiléia, and the Mulundu pegmatite, locality not further specified, Minas Gerais, Brazil
Field-hunting tip
Where it forms: In granite pegmatites. If you start seeing löllingite, eosphorite, scorodite in float, you are in the right ground. Typical habit: fibrous. Train your eye for that shape before scanning the outcrop.
Common questions
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What rocks look like karibibite?+
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Find karibibite on the map
RockHoundR shows mapped rockhounding spots, access rules, and lets you log every find.
