Ferrivauxite is an extremely rare phosphate mineral typically found as radial sprays of golden brown, bladed crystals. It is almost exclusively found in association with other rare secondary phosphate minerals in the tin-rich mines of Bolivia. Collectors prize it for its delicate habit and restricted occurrence in phosphate-rich mineral assemblages.
Is this ferrivauxite?
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 ferrivauxite with a known reference. Ferrivauxite 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. Streak: pale yellow-brown.
- 3Read the lusterHold the specimen under a strong light. Luster: vitreous.
- 4Match the color rangeCompare against the expected color range: golden brown.
- 5Look at form & habitCrystal system: triclinic. Typical habit: radial aggregates of bladed crystals, crusts.
Often confused with
Ferrivauxite vs. its common look-alikes, and how to tell them apart in the field.
How to tell apart: Streak differs, so Ferrivauxite leaves pale yellow-brown, Vauxite leaves white.
How to tell apart: Streak differs, so Ferrivauxite leaves pale yellow-brown, Paravauxite leaves white.
How to tell apart: Streak differs, so Ferrivauxite leaves pale yellow-brown, Metavauxite leaves white.
Often found alongside ferrivauxite
Minerals reported to co-occur with ferrivauxite. Spotting these in float or country rock is a strong cue you are in the right ground.
All properties
- Chemical formula
- FeAl₂(PO₄)₂(OH)₃·5H₂O
- Mohs hardness
- ~3.5
- Density
- 2.40 g/cm³
- Colors
- Streak
- Pale yellow-brown
- Luster
- Vitreous
- Transparency
- Transparent to translucent
- Crystal system
- Triclinic
- Crystal habit
- Radial aggregates of bladed crystals, crusts
- Cleavage
- None
- Rarity
- Rare
- Uses
- Collector
- Host rock
- Formed by oxidation of primary fluorapatite and other phosphates in a hydrothermal tin deposit
Where rockhounds find ferrivauxite
Classic worldwide localities
- Llallagua tin deposit,Potosí, Bolivia
Field-hunting tip
Where it forms: Formed by oxidation of primary fluorapatite and other phosphates in a hydrothermal tin deposit. If you start seeing sigloite, crandallite in float, you are in the right ground. Typical habit: radial aggregates of bladed crystals, crusts. Train your eye for that shape before scanning the outcrop.
Common questions
How do you identify ferrivauxite?+
Where is ferrivauxite found?+
What rocks look like ferrivauxite?+
What minerals are found with ferrivauxite?+
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Find ferrivauxite on the map
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