Volaschioite is a very rare iron sulfate mineral typically occurring as soft, earthy yellow coatings or powdery aggregates. It is found as an alteration product of pyrite in specific hydrothermal vein systems. Collectors generally identify it through its association with other secondary iron sulfates in localized Italian deposits.
Is this volaschioite?
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 volaschioite with a known reference. Volaschioite sits at Mohs 2, softer than the next harder reference, harder than the previous one.
- 2Check the streakDrag the specimen across an unglazed porcelain plate. Streak: orange.
- 3Read the lusterHold the specimen under a strong light. Luster: vitreous to resinous.
- 4Match the color rangeCompare against the expected color range: yellowish-orange.
- 5Look at form & habitCrystal system: monoclinic. Typical habit: powdery aggregates, crusts.
Often confused with
Volaschioite vs. its common look-alikes, and how to tell them apart in the field.
How to tell apart: Streak differs, so Volaschioite leaves orange, Jarosite leaves pale yellow; luster reads vitreous to resinous on Volaschioite and subadamantine to vitreous, resinous on fractures on Jarosite.
How to tell apart: Streak differs, so Volaschioite leaves orange, Copiapite leaves pale yellow; luster reads vitreous to resinous on Volaschioite and pearly on {010} on Copiapite.
Often found alongside volaschioite
Minerals reported to co-occur with volaschioite. Spotting these in float or country rock is a strong cue you are in the right ground.
All properties
- Chemical formula
- Fe₄(SO₄)(OH)₁₀
- Mohs hardness
- 2
- Density
- 3.03 g/cm³
- Colors
- Streak
- Orange
- Luster
- Vitreous to resinous
- Transparency
- Transparent
- Crystal system
- Monoclinic
- Crystal habit
- Powdery aggregates, crusts
- Cleavage
- Perfect on {100}
- Rarity
- Rare
- Uses
- Collector
- Host rock
- An oxidation product of pyrite in tunnels through a magnetite-pyrite deposit
Where rockhounds find volaschioite
Classic worldwide localities
- Cava del Ferro mining complex, Fornovolasco, Apuan Alps, Tuscany, Italy
Field-hunting tip
Where it forms: An oxidation product of pyrite in tunnels through a magnetite-pyrite deposit. If you start seeing pyrite, fibroferrite, goethite in float, you are in the right ground. Typical habit: powdery aggregates, crusts. Train your eye for that shape before scanning the outcrop.
Common questions
How do you identify volaschioite?+
Where is volaschioite found?+
What rocks look like volaschioite?+
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Find volaschioite on the map
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