Microsommite is a rare tectosilicate mineral primarily known from the ejecta blocks of Mount Vesuvius and Monte Somma. It typically appears as small, colorless to yellowish hexagonal prisms associated with other alkaline volcanic minerals.
Is this microsommite?
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 microsommite with a known reference. Microsommite sits at Mohs 6 — softer than the next harder reference, harder than the previous one.
- 2Check the streakDrag the specimen across an unglazed porcelain plate. Microsommite leaves a white streak.
- 3Read the lusterHold the specimen under a strong light. Microsommite typically shows a vitreous luster.
- 4Match the color rangeCompare against the expected color range: colorless, white, yellow.
- 5Look at form & habitCrystal system: hexagonal. Typical habit: prismatic crystals.
Often confused with
Microsommite vs. its common look-alikes — and how to tell them apart in the field.
Often found alongside microsommite
Minerals reported to co-occur with microsommite. Spotting these in float or country rock is a strong cue you are in the right ground.
All properties
- Chemical formula
- (Na,Ca,K)₈(Si,Al)₁₂O₂₄(Cl,SO₄,CO₃)₂₋₃
- Mohs hardness
- 6
- Density
- 2.53-2.58 g/cm³
- Streak
- White
- Luster
- Vitreous
- Transparency
- Transparent
- Crystal system
- Hexagonal
- Crystal habit
- Prismatic Crystals
- Cleavage
- Distinct On {1010}
- Fluorescence
- Bright Yellow Under SW UV
- Rarity
- Rare
- Uses
- Collector
- Host rock
- Volcanic Ejecta
- Typical price
- $50-300 per specimen
Where rockhounds find microsommite
Classic worldwide localities
- Monte Somma, Italy
- Vesuvius, Italy
Field-hunting tip
Look in volcanic ejecta country — that is the host setting where microsommite typically forms. If you start seeing nepheline, sanidine, pyroxene 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 microsommite?+
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How much is microsommite worth?+
What rocks look like microsommite?+
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Find microsommite on the map
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