Millosevichite is a rare sulfate mineral typically found as a volcanic efflorescence or crust near active fumaroles. Collectors usually find it as a delicate, powdery, or earthy mass that is highly susceptible to humidity and water, often requiring airtight storage.
Is this millosevichite?
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 millosevichite with a known reference. Millosevichite 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. Millosevichite leaves a white streak.
- 3Read the lusterHold the specimen under a strong light. Millosevichite typically shows a dull luster.
- 4Match the color rangeCompare against the expected color range: white, pale yellow, pale green.
- 5Look at form & habitCrystal system: orthorhombic. Typical habit: encrustations, granular, powdery efflorescence.
Often confused with
Millosevichite vs. its common look-alikes — and how to tell them apart in the field.
How to tell apart: Luster reads dull on Millosevichite and vitreous on Coquimbite.
How to tell apart: Luster reads dull on Millosevichite and vitreous on Halotrichite.
How to tell apart: Luster reads dull on Millosevichite and vitreous on Melanterite.
Often found alongside millosevichite
Minerals reported to co-occur with millosevichite. Spotting these in float or country rock is a strong cue you are in the right ground.
All properties
- Chemical formula
- (Fe³⁺,Al)₂(SO₄)₃
- Mohs hardness
- 2-3
- Density
- 2.32 g/cm³
- Streak
- White
- Luster
- Dull
- Transparency
- Opaque
- Crystal system
- Orthorhombic
- Crystal habit
- Encrustations, Granular, Powdery Efflorescence
- Cleavage
- None
- Rarity
- Rare
- Uses
- Collector
- Host rock
- Fumarolic Deposits and Volcanic Vents
- Typical price
- $20-100 thumbnail specimen
Where rockhounds find millosevichite
Classic worldwide localities
- La Fossa crater, Vulcano, Italy
- Alum Cave Bluff, Tennessee, USA
- Rio Tinto, Spain
Field-hunting tip
Look in fumarolic deposits and volcanic vents country — that is the host setting where millosevichite typically forms. If you start seeing alunogen, sulfur, gypsum in float, you are in the right ground. Field specimens usually show a encrustations, granular, powdery efflorescence habit, so train your eye for that shape before scanning the outcrop.
Common questions
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Find millosevichite on the map
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