Huemulite is a rare hydrated sodium magnesium vanadate that typically forms as bright orange efflorescent crusts on sandstone walls in mines. It is highly water-soluble, meaning it should be stored in a dry environment to prevent degradation.
Is this huemulite?
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 huemulite with a known reference. Huemulite sits at Mohs 2.5-3, softer than the next harder reference, harder than the previous one.
- 2Check the streakDrag the specimen across an unglazed porcelain plate. Streak: yellow.
- 3Read the lusterHold the specimen under a strong light. Luster: dull.
- 4Match the color rangeCompare against the expected color range: yellow, yellow orange, red orange.
- 5Look at form & habitCrystal system: triclinic. Typical habit: encrustations.
Often confused with
Huemulite vs. its common look-alikes, and how to tell them apart in the field.
How to tell apart: Streak differs, so Huemulite leaves yellow, Pascoite leaves cadmium-yellow; luster reads dull on Huemulite and vitreous to subadamantine on Pascoite.
How to tell apart: Streak differs, so Huemulite leaves yellow, Sherwoodite leaves pale blue; luster reads dull on Huemulite and vitreous to earthy on Sherwoodite.
Often found alongside huemulite
Minerals reported to co-occur with huemulite. Spotting these in float or country rock is a strong cue you are in the right ground.
All properties
- Chemical formula
- Na₄MgV₁₀O₂₈·24H₂O
- Mohs hardness
- 2.5-3
- Density
- 2.39 g/cm³
- Streak
- Yellow
- Luster
- Dull
- Transparency
- Semitransparent
- Crystal system
- Triclinic
- Crystal habit
- Encrustations
- Cleavage
- Perfect
- Rarity
- Rare
- Uses
- Collector
- Host rock
- Formed after opening Cu–U deposits in sandstones and conglomerates; the vanadium may be derived from associated asphalt
Where rockhounds find huemulite
Classic worldwide localities
- Agua Botada, Huemul, and Agua Botada Sur mines, Malargüe district, Mendoza Province, Argentina
Field-hunting tip
Where it forms: Formed after opening Cu–U deposits in sandstones and conglomerates; the vanadium may be derived from associated asphalt. If you start seeing hummerite, rossite, thenardite in float, you are in the right ground. Typical habit: encrustations. Train your eye for that shape before scanning the outcrop.
Common questions
How do you identify huemulite?+
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Is huemulite safe to handle?+
What rocks look like huemulite?+
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Find huemulite on the map
RockHoundR shows mapped rockhounding spots, access rules, and lets you log every find.
