Adranosite is a rare sulfate mineral typically found as small crusts or delicate crystals within volcanic fumarole vents. It is primarily identified by its occurrence at the La Fossa crater on Vulcano, where it precipitates directly from volcanic gases.
Is this adranosite?
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 adranosite with a known reference. Adranosite sits at Mohs 2-3, softer than the next harder reference, harder than the previous one.
- 2Check the streakDrag the specimen across an unglazed porcelain plate. Streak: white.
- 3Read the lusterHold the specimen under a strong light. Luster: vitreous.
- 4Match the color rangeCompare against the expected color range: white, colorless.
- 5Look at form & habitCrystal system: tetragonal. Typical habit: tabular crystals.
Often confused with
Adranosite vs. its common look-alikes, and how to tell them apart in the field.
Often found alongside adranosite
Minerals reported to co-occur with adranosite. Spotting these in float or country rock is a strong cue you are in the right ground.
All properties
- Chemical formula
- (NH₄)₄NaAl₂(SO₄)₄Cl(OH)₂
- Mohs hardness
- 2-3
- Density
- 2.15 g/cm³
- Streak
- White
- Luster
- Vitreous
- Transparency
- Translucent
- Crystal system
- Tetragonal
- Crystal habit
- Tabular crystals
- Rarity
- Rare
- Uses
- Collector
- Host rock
- A sublimate on pyroclastic breccia around an active volcanic fumarole
Where rockhounds find adranosite
Classic worldwide localities
- La Fossa crater, Vulcano, Aeolian Islands, Sicily, Italy
Field-hunting tip
Where it forms: A sublimate on pyroclastic breccia around an active volcanic fumarole. If you start seeing aiolosite, alunite, anhydrite in float, you are in the right ground. Typical habit: tabular crystals. Train your eye for that shape before scanning the outcrop.
Common questions
How do you identify adranosite?+
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Find adranosite on the map
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