Ciriottiite is a rare sulfosalt mineral primarily found in manganese-rich hydrothermal deposits in Italy. It typically occurs as small, dark brown to black anhedral grains associated with manganese oxides and various sulfides. Due to its extreme rarity and very small grain size, it is almost exclusively sought after by advanced systematic mineral collectors.

Hardness

3.5

Mohs

Luster

Submetallic

Streak

Brown

Transparency

Opaque

mineralrare

Ciriottiite

Hardness: 3.5
Luster: Submetallic
Streak: Brown
Transparency: Opaque

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Is this ciriottiite?

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 ciriottiite with a known reference. Ciriottiite sits at Mohs 3.5 — softer than the next harder reference, harder than the previous one.
2
Check the streak
Drag the specimen across an unglazed porcelain plate. Ciriottiite leaves a brown streak.
3
Read the luster
Hold the specimen under a strong light. Ciriottiite typically shows a submetallic luster.
4
Match the color range
Compare against the expected color range: dark brown, black.
5
Look at form & habit
Crystal system: monoclinic. Typical habit: anhedral to subhedral grains.

Often confused with

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

mineral

Tetrahedrite

Mohs 3-4

How to tell apart: Streak differs — Ciriottiite leaves brown, Tetrahedrite leaves black; luster reads submetallic on Ciriottiite and metallic on Tetrahedrite.

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Often found alongside ciriottiite

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

All properties

Chemical formula: Na₂CuFe₂As₄S₁₀
Mohs hardness: 3.5
Density: 4.55 g/cm³
Colors: Dark Brown Black
Streak: Brown
Luster: Submetallic
Transparency: Opaque
Crystal system: Monoclinic
Crystal habit: Anhedral to Subhedral Grains
Cleavage: None
Rarity: Rare
Uses: Collector
Host rock: Hydrothermal Manganese Ore Deposits
Typical price: $100-500 depending on specimen quality

Where rockhounds find ciriottiite

Classic worldwide localities

Monte Nero, Val Graveglia, Liguria, Italy

Field-hunting tip

Look in hydrothermal manganese ore deposits country — that is the host setting where ciriottiite typically forms. If you start seeing braunite, quartz, calcite in float, you are in the right ground. Field specimens usually show a anhedral to subhedral grains habit, so train your eye for that shape before scanning the outcrop.

Common questions

How do you identify ciriottiite?+

Mohs hardness is 3.5. It typically shows a submetallic luster. The streak is brown. Common colors include dark brown, black.

Where is ciriottiite found?+

Notable localities include Monte Nero, Val Graveglia, Liguria, Italy.

How much is ciriottiite worth?+

Typical asking prices fall in the range of $100-500 depending on specimen quality. Quality, size, and provenance can move individual specimens well outside that range.

Is ciriottiite safe to handle?+

It contains toxic constituents. Contains arsenic and copper; wash hands thoroughly after handling and avoid dust inhalation. Handle with care, avoid grinding or breathing dust, and store separately.

What rocks look like ciriottiite?+

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

What minerals are found with ciriottiite?+

Ciriottiite commonly co-occurs with braunite, quartz, calcite, hematite. Spotting any of these in float or country rock is a useful trip signal.

What kind of rock does ciriottiite form in?+

Ciriottiite typically forms in hydrothermal manganese ore deposits. Working float back to the host body is the standard way to chase a fresh occurrence.

What is ciriottiite used for?+

Ciriottiite is used in collector.

Find ciriottiite on the map

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