Rosenbergite is a rare aluminum fluoride hydrate mineral primarily found as a sublimation product in fumaroles. It typically occurs as small, colorless to white prismatic crystals and is noted for its relative softness and specific formation environment.
Is this rosenbergite?
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 rosenbergite with a known reference. Rosenbergite sits at Mohs 3 — softer than the next harder reference, harder than the previous one.
- 2Check the streakDrag the specimen across an unglazed porcelain plate. Rosenbergite leaves a white streak.
- 3Read the lusterHold the specimen under a strong light. Rosenbergite typically shows a vitreous luster.
- 4Match the color rangeCompare against the expected color range: white, colorless.
- 5Look at form & habitCrystal system: tetragonal. Typical habit: prismatic crystals.
Often confused with
Rosenbergite vs. its common look-alikes — and how to tell them apart in the field.
Often found alongside rosenbergite
Minerals reported to co-occur with rosenbergite. Spotting these in float or country rock is a strong cue you are in the right ground.
All properties
- Chemical formula
- AlF₃·3H₂O
- Mohs hardness
- 3
- Density
- 2.71 g/cm³
- Streak
- White
- Luster
- Vitreous
- Transparency
- Transparent
- Crystal system
- Tetragonal
- Crystal habit
- Prismatic Crystals
- Cleavage
- None
- Rarity
- Rare
- Uses
- Collector
- Host rock
- Fumaroles
- Typical price
- $50-300 per specimen
Where rockhounds find rosenbergite
Classic worldwide localities
- Vulcano, Lipari Islands, Italy
Field-hunting tip
Look in fumaroles country — that is the host setting where rosenbergite typically forms. If you start seeing aluminite, gypsum, sulfur in float, you are in the right ground. Field specimens usually show a prismatic crystals habit, so train your eye for that shape before scanning the outcrop.
Common questions
How do you identify rosenbergite?+
Where is rosenbergite found?+
How much is rosenbergite worth?+
What rocks look like rosenbergite?+
What minerals are found with rosenbergite?+
What kind of rock does rosenbergite form in?+
What is rosenbergite used for?+
Find rosenbergite on the map
RockHoundR shows mapped rockhounding spots, access rules, and lets you log every find.
