Umbrianite is an exceptionally rare sodium silicate mineral found primarily within the ejecta of the Somma-Vesuvius volcanic complex. Collectors usually encounter it as small, colorless to pale yellow tabular crystals embedded in volcanic matrices.
Is this umbrianite?
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 umbrianite with a known reference. Umbrianite sits at Mohs 3.5, softer than the next harder reference, harder than the previous one.
- 2Check the streakDrag the specimen across an unglazed porcelain plate. Umbrianite leaves a white streak.
- 3Read the lusterHold the specimen under a strong light. Umbrianite typically shows a vitreous luster.
- 4Match the color rangeCompare against the expected color range: colorless, white, yellow.
- 5Look at form & habitCrystal system: trigonal. Typical habit: tabular crystals.
Often confused with
Umbrianite vs. its common look-alikes, and how to tell them apart in the field.
Often found alongside umbrianite
Minerals reported to co-occur with umbrianite. Spotting these in float or country rock is a strong cue you are in the right ground.
All properties
- Chemical formula
- Na₈(Si₆O₁₈)Cl₂
- Mohs hardness
- 3.5
- Density
- 2.81 g/cm³
- Streak
- White
- Luster
- Vitreous
- Transparency
- Transparent
- Crystal system
- Trigonal
- Crystal habit
- Tabular Crystals
- Cleavage
- Perfect
- Rarity
- Rare
- Uses
- Collector
- Host rock
- Volcanic Ejecta
- Typical price
- $50-300 per specimen
Where rockhounds find umbrianite
Classic worldwide localities
- Vesuvius, Italy
- Somma-Vesuvius complex, Italy
Field-hunting tip
Look in volcanic ejecta country, the host setting where umbrianite typically forms. If you start seeing phlogopite, fluorite, sodalite in float, you are in the right ground. Field specimens usually show a tabular crystals habit, so train your eye for that shape before scanning the outcrop.
Common questions
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Find umbrianite on the map
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