Arupite is a rare hydrated nickel phosphate belonging to the vivianite group, occurring as delicate pale green to yellowish-green platy crystals. It is typically found as a secondary mineral in oxidized nickel-rich ore deposits, often appearing as coatings or radial sprays on associated nickel minerals.
Is this arupite?
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 arupite with a known reference. Arupite sits at Mohs 1.5-2, softer than the next harder reference, harder than the previous one.
- 2Check the streakDrag the specimen across an unglazed porcelain plate. Streak: light blue.
- 3Read the lusterHold the specimen under a strong light. Luster: earthy.
- 4Match the color rangeCompare against the expected color range: turquoise blue, blue.
- 5Look at form & habitCrystal system: monoclinic. Typical habit: platy crystals, crusts, radial aggregates.
Often confused with
Arupite vs. its common look-alikes, and how to tell them apart in the field.
How to tell apart: Streak differs, so Arupite leaves light blue, Vivianite leaves white, altering to dark blue, brown; luster reads earthy on Arupite and vitreous, pearly on the cleavage, dull when earthy on Vivianite.
How to tell apart: Streak differs, so Arupite leaves light blue, Annabergite leaves pale green to white; luster reads earthy on Arupite and subadamantine, pearly on cleavages, may be dull, earthy on Annabergite.
Often found alongside arupite
Minerals reported to co-occur with arupite. Spotting these in float or country rock is a strong cue you are in the right ground.
All properties
- Chemical formula
- Ni₃(PO₄)₂·8H₂O
- Mohs hardness
- 1.5-2
- Density
- 2.85 g/cm³
- Colors
- Turquoise blueBlue
- Streak
- Light blue
- Luster
- Earthy
- Transparency
- Translucent
- Crystal system
- Monoclinic
- Crystal habit
- Platy crystals, crusts, radial aggregates
- Cleavage
- Good
- Rarity
- Rare
- Uses
- Collector
- Host rock
- A weathering product of a nickel-rich iron meteorite
Where rockhounds find arupite
Classic worldwide localities
- In the Santa Catherina iron meteorite (type locality)
Field-hunting tip
Where it forms: A weathering product of a nickel-rich iron meteorite. If you start seeing reevesite, honessite, akaganeite in float, you are in the right ground. Typical habit: platy crystals, crusts, radial aggregates. Train your eye for that shape before scanning the outcrop.
Common questions
How do you identify arupite?+
Where is arupite found?+
Is arupite safe to handle?+
What rocks look like arupite?+
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Find arupite on the map
RockHoundR shows mapped rockhounding spots, access rules, and lets you log every find.
