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, 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
How do you identify ferrochiavennite?+
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Find ferrochiavennite on the map
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