Ferrochiavennite is a rare zeolite-group mineral that typically occurs as small prismatic crystals within alkaline pegmatites. It is most easily distinguished from its manganese-dominant analog, chiavennite, through detailed chemical analysis or X-ray diffraction, as their physical appearances are nearly identical.
Is this ferrochiavennite?
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 ferrochiavennite with a known reference. Ferrochiavennite sits at Mohs 4 — softer than the next harder reference, harder than the previous one.
- 2Check the streakDrag the specimen across an unglazed porcelain plate. Ferrochiavennite leaves a white streak.
- 3Read the lusterHold the specimen under a strong light. Ferrochiavennite typically shows a vitreous luster.
- 4Match the color rangeCompare against the expected color range: white, colorless, pale yellow.
- 5Look at form & habitCrystal system: orthorhombic. Typical habit: prismatic crystals.
Often confused with
Ferrochiavennite vs. its common look-alikes — and how to tell them apart in the field.
Often found alongside ferrochiavennite
Minerals reported to co-occur with ferrochiavennite. Spotting these in float or country rock is a strong cue you are in the right ground.
All properties
- Chemical formula
- CaMnFeBe₂(Si₆O₁₆)(OH)₂·4H₂O
- Mohs hardness
- 4
- Density
- 2.5 g/cm³
- Streak
- White
- Luster
- Vitreous
- Transparency
- Transparent
- Crystal system
- Orthorhombic
- Crystal habit
- Prismatic Crystals
- Cleavage
- Good
- Rarity
- Rare
- Uses
- Collector
- Host rock
- Alkaline Pegmatites
- Typical price
- $50-300 per specimen
Where rockhounds find ferrochiavennite
Classic worldwide localities
- Chiavenna, Italy
- Piz Nair, Switzerland
Field-hunting tip
Look in alkaline pegmatites country — that is the host setting where ferrochiavennite typically forms. If you start seeing tvedalite, helvite, quartz 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
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Find ferrochiavennite on the map
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