Cassagnaite is an extremely rare calcium vanadium silicate mineral typically found as small, vibrant reddish-golden brown tabular crystals. It is currently known primarily from its type locality in the Cassagna mine of Italy, where it occurs within manganese-rich metamorphic deposits.

Hardness

Mohs

Luster

Vitreous

Streak

Nearly white

Transparency

Transparent

mineralrare

Cassagnaite

Hardness: 4
Luster: Vitreous
Streak: Nearly white
Transparency: Transparent

No image

Is this cassagnaite?

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 cassagnaite with a known reference. Cassagnaite sits at Mohs 4, softer than the next harder reference, harder than the previous one.
2
Check the streak
Drag the specimen across an unglazed porcelain plate. Streak: nearly 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: golden brown.
5
Look at form & habit
Crystal system: orthorhombic. Typical habit: prismatic, tabular.

Often confused with

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

mineral

Vesuvianite

Mohs 6-7

How to tell apart: Vesuvianite is the harder of the two (Mohs 6-7 vs. 4); streak differs, so Cassagnaite leaves nearly white, Vesuvianite leaves white.

How to tell apart: Garnet is the harder of the two (Mohs 6.5-7.5 vs. 4); streak differs, so Cassagnaite leaves nearly white, Garnet leaves white.

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Often found alongside cassagnaite

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

All properties

Chemical formula: Ca₄Fe₄V₂(OH)₆O₂(Si₃O₁₀)(SiO₄)₂
Mohs hardness: 4
Density: 3.22 g/cm³
Colors: Golden brown
Streak: Nearly white
Luster: Vitreous
Transparency: Transparent
Crystal system: Orthorhombic
Crystal habit: Prismatic, tabular
Cleavage: {001} (or parting)
Rarity: Rare
Uses: Collector
Host rock: Filling fractures in braunite and quartz layered mineralization developed under prehnite-pumpellyite facies metamorphism

Where rockhounds find cassagnaite

Classic worldwide localities

Cassagna mine, Graveglia manganese district, Northern Apennines, Liguria, Italy

Field-hunting tip

Where it forms: Filling fractures in braunite and quartz layered mineralization developed under prehnite-pumpellyite facies metamorphism. If you start seeing braunite, quartz, piemontite in float, you are in the right ground. Typical habit: prismatic, tabular. Train your eye for that shape before scanning the outcrop.

Common questions

How do you identify cassagnaite?+

Mohs hardness is 4. Luster: vitreous. The streak is nearly white. Common colors include golden brown.

Where is cassagnaite found?+

Notable localities include Cassagna mine, Graveglia manganese district, Northern Apennines, Liguria, Italy.

Is cassagnaite safe to handle?+

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

What rocks look like cassagnaite?+

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

What minerals are found with cassagnaite?+

Cassagnaite commonly co-occurs with Braunite, Quartz, Piemontite. Spotting any of these in float or country rock is a useful trip signal.

What kind of rock does cassagnaite form in?+

Where it forms: Filling fractures in braunite and quartz layered mineralization developed under prehnite-pumpellyite facies metamorphism. Working float back to the host body is the standard way to chase a fresh occurrence.

What is cassagnaite used for?+

Cassagnaite is used in collector.

Find cassagnaite on the map

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