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.

Hardness

Mohs

Luster

Vitreous

Streak

White

Transparency

Translucent

mineralrareGismondine Group family

Ferrochiavennite

Hardness: ~3
Luster: Vitreous
Streak: White
Transparency: Translucent

No image

Is this ferrochiavennite?

5-step field check

Run through these checks against the specimen in your hand. The more boxes tick, the more confident the ID.

1
Test the hardness
Try to scratch ferrochiavennite with a known reference. Ferrochiavennite sits at Mohs ~3, softer than the next harder reference, harder than the previous one.
2
Check the streak
Drag the specimen across an unglazed porcelain plate. Streak: white.
3
Read the luster
Hold the specimen under a strong light. Luster: vitreous.
4
Match the color range
Compare against the expected color range: beige, pale-yellow, pale-green.
5
Look at form & habit
Crystal system: monoclinic. 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: Ca₂Fe(Si,Al,Be)₅Be₂O₁₃(OH)₂·2H₂O
Mohs hardness: ~3
Density: 2.67 g/cm³
Colors: Beige Pale-yellow Pale-green
Streak: White
Luster: Vitreous
Transparency: Translucent
Crystal system: Monoclinic
Crystal habit: Prismatic crystals
Cleavage: None
Rarity: Rare
Uses: Collector
Host rock: A late hydrothermal stage mineral in alkaline syenite pegmatite

Where rockhounds find ferrochiavennite

Classic worldwide localities

Norway at Blåfjell, Langangen, Telemark, and the AS Granit larvikite quarry, Tvedalen, Vestfold

Field-hunting tip

Where it forms: A late hydrothermal stage mineral in alkaline syenite pegmatite. If you start seeing albite, magnetite, fayalite in float, you are in the right ground. Typical habit: prismatic crystals. Train your eye for that shape before scanning the outcrop.

Common questions

How do you identify ferrochiavennite?+

Mohs hardness is ~3. Luster: vitreous. The streak is white. Common colors include beige, pale-yellow, pale-green.

Where is ferrochiavennite found?+

Notable localities include Norway at Blåfjell, Langangen, Telemark, and the AS Granit larvikite quarry, Tvedalen, Vestfold.

Is ferrochiavennite safe to handle?+

Ferrochiavennite contains beryllium. Wash your hands afterwards, never grind or breathe the dust, and store it apart from specimens you handle often.

What rocks look like ferrochiavennite?+

Ferrochiavennite is most often confused with Chiavennite. A quick hardness test and a streak check separate the look-alikes faster than color alone.

What minerals are found with ferrochiavennite?+

Ferrochiavennite commonly co-occurs with Albite, Magnetite, Fayalite, Amounts of zircon, Nepheline, Analcime. Spotting any of these in float or country rock is a useful trip signal.

What kind of rock does ferrochiavennite form in?+

Where it forms: A late hydrothermal stage mineral in alkaline syenite pegmatite. Working float back to the host body is the standard way to chase a fresh occurrence.

What is ferrochiavennite used for?+

Ferrochiavennite is used in collector.

Find ferrochiavennite on the map

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