Marinellite is a rare silicate mineral belonging to the cancrinite group, typically found in volcanic rocks in the Alban Hills region of Italy. It usually occurs as small, colorless or white prismatic crystals embedded in volcanic matrices. Collectors prize it primarily as a rare locality-specific species from the Italian alkaline volcanic provinces.
Is this marinellite?
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 marinellite with a known reference. Marinellite sits at Mohs 5-6 — softer than the next harder reference, harder than the previous one.
- 2Check the streakDrag the specimen across an unglazed porcelain plate. Marinellite leaves a white streak.
- 3Read the lusterHold the specimen under a strong light. Marinellite typically shows a vitreous luster.
- 4Match the color rangeCompare against the expected color range: white, colorless.
- 5Look at form & habitCrystal system: trigonal. Typical habit: prismatic crystals, anhedral grains.
Often confused with
Marinellite vs. its common look-alikes — and how to tell them apart in the field.
Often found alongside marinellite
Minerals reported to co-occur with marinellite. Spotting these in float or country rock is a strong cue you are in the right ground.
All properties
- Chemical formula
- (Na,K,Ca)₈(Si,Al)₁₂O₂₄(SO₄,Cl,OH)₂·nH₂O
- Mohs hardness
- 5-6
- Density
- 2.28 g/cm³
- Streak
- White
- Luster
- Vitreous
- Transparency
- Translucent
- Crystal system
- Trigonal
- Crystal habit
- Prismatic Crystals, Anhedral Grains
- Cleavage
- Distinct
- Rarity
- Rare
- Uses
- Collector
- Host rock
- Volcanic Ejecta, Alkaline Igneous Rocks
- Typical price
- $20-100 per specimen
Where rockhounds find marinellite
Classic worldwide localities
- Alban Hills, Italy
- Latium, Italy
Field-hunting tip
Look in volcanic ejecta, alkaline igneous rocks country — that is the host setting where marinellite typically forms. If you start seeing leucite, augite, phlogopite in float, you are in the right ground. Field specimens usually show a prismatic crystals, anhedral grains habit, so train your eye for that shape before scanning the outcrop.
Common questions
How do you identify marinellite?+
Where is marinellite found?+
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What rocks look like marinellite?+
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Find marinellite on the map
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