Chiavennite is a rare beryllium-bearing zeolite mineral that typically forms prismatic, radiating crystal sprays. It is most commonly identified in hydrothermal veins or cavities within alkaline igneous rocks and is highly sought after by mineral collectors specializing in rare species.

Hardness

Mohs

Luster

Vitreous to pearly

Streak

White to pale ocher

Transparency

Translucent

mineralrareZeolite Group family

Chiavennite

Hardness: ~3
Luster: Vitreous to pearly
Streak: White to pale ocher
Transparency: Translucent

Is this chiavennite?

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 chiavennite with a known reference. Chiavennite 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 to pale ocher.
3
Read the luster
Hold the specimen under a strong light. Luster: vitreous to pearly.
4
Match the color range
Compare against the expected color range: yellow, orange, red orange.
5
Look at form & habit
Crystal system: orthorhombic. Typical habit: prismatic crystals, radial aggregates.

Often confused with

Chiavennite vs. its common look-alikes, and how to tell them apart in the field.

mineral

Epistilbite

Mohs 4

How to tell apart: Epistilbite is the harder of the two (Mohs 4 vs. ~3).

Often found alongside chiavennite

Minerals reported to co-occur with chiavennite. Spotting these in float or country rock is a strong cue you are in the right ground.

All properties

Chemical formula: CaMnBe₂(Si₅O₁₃)(OH)₂·2H₂O
Mohs hardness: ~3
Density: 2.56-2.64 g/cm³
Colors: Yellow Orange Red orange
Streak: White to pale ocher
Luster: Vitreous to pearly
Transparency: Translucent
Crystal system: Orthorhombic
Crystal habit: Prismatic crystals, radial aggregates
Cleavage: Good to perfect on {100}, {010}, and {001}
Rarity: Rare
Uses: Collector
Host rock: Coating beryl in late-stage pegmatites (Tanno, Italy); in vugs in syenite pegmatites (Norway)

Where rockhounds find chiavennite

Classic worldwide localities

Tanno, Chiavenna, Lombardy, Italy
Heia and Vevja larvikite quarries, near Larvik, Tvedalen district, Norway
Blåfjell, Langangen, and in the Saga larvikite quarry, Porsgrunn, Langesundsfjord, Norway
Bakkane, Brunlanes, Norway
Utö Island, Sweden

Field-hunting tip

Where it forms: Coating beryl in late-stage pegmatites (Tanno, Italy); in vugs in syenite pegmatites (Norway). If you start seeing beryl, bavenite, analcime in float, you are in the right ground. Typical habit: prismatic crystals, radial aggregates. Train your eye for that shape before scanning the outcrop.

Common questions

How do you identify chiavennite?+

Mohs hardness is ~3. Luster: vitreous to pearly. The streak is white to pale ocher. Common colors include yellow, orange, red orange.

Where is chiavennite found?+

Notable localities include Tanno, Chiavenna, Lombardy, Italy; Heia and Vevja larvikite quarries, near Larvik, Tvedalen district, Norway; Blåfjell, Langangen, and in the Saga larvikite quarry, Porsgrunn, Langesundsfjord, Norway; Bakkane, Brunlanes, Norway; Utö Island, Sweden.

Is chiavennite safe to handle?+

Chiavennite 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 chiavennite?+

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

What minerals are found with chiavennite?+

Chiavennite commonly co-occurs with Beryl, Bavenite, Analcime, Aegirine, Helvite, Eudidymite. Spotting any of these in float or country rock is a useful trip signal.

What kind of rock does chiavennite form in?+

Where it forms: Coating beryl in late-stage pegmatites (Tanno, Italy); in vugs in syenite pegmatites (Norway). Working float back to the host body is the standard way to chase a fresh occurrence.

What is chiavennite used for?+

Chiavennite is used in collector.

Find chiavennite on the map

RockHoundR shows mapped rockhounding spots, access rules, and lets you log every find.