Arsenudinaite is a rare sodium magnesium arsenate, typically beige or brownish-yellowish. It is a sublimate at an active volcanic fumarole. It was first described from the Arsenatnaya fumarole, Kamchatka peninsula, Far-Eastern Region, Russia.
Is this arsenudinaite?
4-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 arsenudinaite with a known reference. Arsenudinaite sits at Mohs 3.5-4, softer than the next harder reference, harder than the previous one.
- 2Read the lusterHold the specimen under a strong light. Luster: vitreous.
- 3Match the color rangeCompare against the expected color range: beige, brownish-yellowish, colorless.
- 4Look at form & habitCrystal system: tetragonal. Typical habit: tabular crystals, massive, granular.
Often confused with
Arsenudinaite vs. its common look-alikes, and how to tell them apart in the field.
How to tell apart: Luster reads vitreous on Arsenudinaite and metallic on Palladseite.
How to tell apart: Sperrylite is the harder of the two (Mohs 6-7 vs. 3.5-4); luster reads vitreous on Arsenudinaite and metallic on Sperrylite.
Often found alongside arsenudinaite
Minerals reported to co-occur with arsenudinaite. Spotting these in float or country rock is a strong cue you are in the right ground.
All properties
- Chemical formula
- NaMg₄(AsO₄)₃
- Mohs hardness
- 3.5-4
- Density
- 3.816 g/cm³
- Luster
- Vitreous
- Transparency
- Transparent
- Crystal system
- Tetragonal
- Crystal habit
- Tabular crystals, massive, granular
- Rarity
- Rare
- Uses
- Collector
- Host rock
- fumarolic volcanic deposits
Where rockhounds find arsenudinaite
Classic worldwide localities
- Arsenatnaya fumarole, Second scoria cone of the Northern Breakthrough of the Great Tolbachik Fissure Eruption, Tolbachik volcano, Kamchatka peninsula, Far-Eastern Region, Russia
Field-hunting tip
Where it forms: fumarolic volcanic deposits. If you start seeing sopcheite, temagamite, palladseite in float, you are in the right ground. Typical habit: tabular crystals, massive, granular. Train your eye for that shape before scanning the outcrop.
Common questions
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Find arsenudinaite on the map
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