Cupropearceite is a rare copper-dominant member of the pearceite group, appearing as dark, metallic hexagonal plates or massive aggregates. It is typically found in low-to-medium temperature hydrothermal sulfide deposits and requires chemical analysis or X-ray diffraction to reliably distinguish from other members of the tennantite-pearceite series.

Hardness

Mohs

Luster

Metallic

Streak

Black

Transparency

Opaque

mineralrarePearceite-Tennantite Series family

Cupropearceite

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

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Is this cupropearceite?

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 cupropearceite with a known reference. Cupropearceite 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: black.
3
Read the luster
Hold the specimen under a strong light. Luster: metallic.
4
Match the color range
Compare against the expected color range: black, iron-black.
5
Look at form & habit
Crystal system: trigonal. Typical habit: tabular crystals, hexagonal plates, massive.

Often confused with

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

Often found alongside cupropearceite

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

All properties

Chemical formula: (Cu,Ag)₁₆As₂S₁₁
Mohs hardness: 3
Density: 6.2 g/cm³
Colors: Black Iron-black
Streak: Black
Luster: Metallic
Transparency: Opaque
Crystal system: Trigonal
Crystal habit: Tabular crystals, hexagonal plates, massive
Cleavage: None
Rarity: Rare
Uses: Collector
Host rock: Pearceite-polybasite group

Where rockhounds find cupropearceite

Classic worldwide localities

Sarbai Mine, Turgai region, Kazakhstan (type locality)

Field-hunting tip

Where it forms: Pearceite-polybasite group. If you start seeing tennantite, galena, sphalerite in float, you are in the right ground. Typical habit: tabular crystals, hexagonal plates, massive. Train your eye for that shape before scanning the outcrop.

Common questions

How do you identify cupropearceite?+

Mohs hardness is 3. Luster: metallic. The streak is black. Common colors include black, iron-black.

Where is cupropearceite found?+

Notable localities include Sarbai Mine, Turgai region, Kazakhstan (type locality).

Is cupropearceite safe to handle?+

Cupropearceite contains arsenic and copper and calls for real care. Contains arsenic and copper; avoid dust inhalation and wash hands thoroughly after handling specimens.

What rocks look like cupropearceite?+

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

What minerals are found with cupropearceite?+

Cupropearceite commonly co-occurs with Tennantite, Galena, Sphalerite, Calcite, Dolomite. Spotting any of these in float or country rock is a useful trip signal.

What kind of rock does cupropearceite form in?+

Where it forms: Pearceite-polybasite group. Working float back to the host body is the standard way to chase a fresh occurrence.

What is cupropearceite used for?+

Cupropearceite is used in collector.

Find cupropearceite on the map

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