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, 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
RockHoundR shows mapped rockhounding spots, access rules, and lets you log every find.
