Montesommaite is an extremely rare zeolite found almost exclusively in the volcanic rocks of the Monte Somma-Vesuvius complex in Italy. It typically forms as small, colorless, equant crystals within cavities of alkaline volcanic material. Collectors primarily encounter it as micro-specimens associated with other rare volcanic minerals.
Is this montesommaite?
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 montesommaite with a known reference. Montesommaite sits at Mohs 4.5, softer than the next harder reference, harder than the previous one.
- 2Check the streakDrag the specimen across an unglazed porcelain plate. Montesommaite leaves a white streak.
- 3Read the lusterHold the specimen under a strong light. Montesommaite typically shows a vitreous luster.
- 4Match the color rangeCompare against the expected color range: colorless, white.
- 5Look at form & habitCrystal system: orthorhombic. Typical habit: equant crystals.
Often confused with
Montesommaite vs. its common look-alikes, and how to tell them apart in the field.
Often found alongside montesommaite
Minerals reported to co-occur with montesommaite. Spotting these in float or country rock is a strong cue you are in the right ground.
All properties
- Chemical formula
- K₉(Al₉Si₂₃O₆₄)·10H₂O
- Mohs hardness
- 4.5
- Density
- 2.16 g/cm³
- Streak
- White
- Luster
- Vitreous
- Transparency
- Transparent
- Crystal system
- Orthorhombic
- Crystal habit
- Equant Crystals
- Cleavage
- None
- Rarity
- Rare
- Uses
- Collector
- Host rock
- Volcanic Ejecta
- Typical price
- $50-300 per specimen
Where rockhounds find montesommaite
Classic worldwide localities
- Monte Somma, Italy
- Vesuvius, Italy
Field-hunting tip
Look in volcanic ejecta country, the host setting where montesommaite typically forms. If you start seeing nepheline, leucite, garnet in float, you are in the right ground. Field specimens usually show a equant crystals habit, so train your eye for that shape before scanning the outcrop.
Common questions
How do you identify montesommaite?+
Where is montesommaite found?+
How much is montesommaite worth?+
What rocks look like montesommaite?+
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Find montesommaite on the map
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