Catamarcaite is a very rare copper-germanium-tungsten sulfide mineral known primarily from the Capillitas mine in Argentina. It typically appears as small, grey to black metallic grains associated with other rare germanium-bearing sulfides.

Hardness

3-3.5

Mohs

Luster

Metallic

Streak

Black

Transparency

Opaque

mineralrare

Catamarcaite

Hardness: 3-3.5
Luster: Metallic
Streak: Black
Transparency: Opaque

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Is this catamarcaite?

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 catamarcaite with a known reference. Catamarcaite sits at Mohs 3-3.5, softer than the next harder reference, harder than the previous one.
2
Check the streak
Drag the specimen across an unglazed porcelain plate. Catamarcaite leaves a black streak.
3
Read the luster
Hold the specimen under a strong light. Catamarcaite typically shows a metallic luster.
4
Match the color range
Compare against the expected color range: gray, black.
5
Look at form & habit
Crystal system: tetragonal. Typical habit: granular.

Often confused with

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

How to tell apart: Renierite is the harder of the two (Mohs 4.5 vs. 3-3.5).

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Often found alongside catamarcaite

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

All properties

Chemical formula: Cu₆GeWS₈
Mohs hardness: 3-3.5
Density: 5.35 g/cm³
Colors: Gray Black
Streak: Black
Luster: Metallic
Transparency: Opaque
Crystal system: Tetragonal
Crystal habit: Granular
Cleavage: None
Rarity: Rare
Uses: Collector
Host rock: Hydrothermal Veins
Typical price: $50-300 per specimen

Where rockhounds find catamarcaite

Classic worldwide localities

Capillitas Mining District, Argentina

Field-hunting tip

Look in hydrothermal veins country, the host setting where catamarcaite typically forms. If you start seeing germanite, renierite, stannite in float, you are in the right ground. Field specimens usually show a granular habit, so train your eye for that shape before scanning the outcrop.

Common questions

How do you identify catamarcaite?+

Mohs hardness is 3-3.5. It typically shows a metallic luster. The streak is black. Common colors include gray, black.

Where is catamarcaite found?+

Notable localities include Capillitas Mining District, Argentina.

How much is catamarcaite worth?+

Typical asking prices fall in the range of $50-300 per specimen. Quality, size, and provenance can move individual specimens well outside that range.

Is catamarcaite safe to handle?+

It contains toxic constituents. Contains copper and potentially harmful trace elements; handle with care and wash hands after touching, as with most sulfide minerals. Handle with care, avoid grinding or breathing dust, and store separately.

What rocks look like catamarcaite?+

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

What minerals are found with catamarcaite?+

Catamarcaite commonly co-occurs with Germanite, Renierite, Stannite, Chalcopyrite. Spotting any of these in float or country rock is a useful trip signal.

What kind of rock does catamarcaite form in?+

Catamarcaite typically forms in hydrothermal veins. Working float back to the host body is the standard way to chase a fresh occurrence.

What is catamarcaite used for?+

Catamarcaite is used in collector.

Find catamarcaite on the map

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