Coiraite is an exceptionally rare sulfosalt mineral primarily found in the tin-rich polymetallic deposits of Bolivia. It typically occurs as small, dark, tabular to platy crystals that are structurally related to the cylindrite group, often requiring analytical techniques for positive field identification.

Hardness

2.5

Mohs

Luster

Metallic

Streak

Black

Transparency

Opaque

mineralrareCylindrite Group family

Coiraite

Hardness: 2.5
Luster: Metallic
Streak: Black
Transparency: Opaque

Is this coiraite?

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 coiraite with a known reference. Coiraite sits at Mohs 2.5 — softer than the next harder reference, harder than the previous one.
2
Check the streak
Drag the specimen across an unglazed porcelain plate. Coiraite leaves a black streak.
3
Read the luster
Hold the specimen under a strong light. Coiraite typically shows a metallic luster.
4
Match the color range
Compare against the expected color range: black, lead-gray.
5
Look at form & habit
Crystal system: triclinic. Typical habit: platy crystals, tabular, striated.

Often confused with

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

Often found alongside coiraite

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

All properties

Chemical formula: (Pb,Sn)₄Sn₂FeSb₂S₁₄
Mohs hardness: 2.5
Density: 5.68 g/cm³
Colors: Black Lead-gray
Streak: Black
Luster: Metallic
Transparency: Opaque
Crystal system: Triclinic
Crystal habit: Platy Crystals, Tabular, Striated
Cleavage: Perfect On {001}
Rarity: Rare
Uses: Collector
Host rock: Hydrothermal Tin-silver Veins
Typical price: $50-300 per specimen

Where rockhounds find coiraite

Classic worldwide localities

Oruro Department, Bolivia
Cerro de Potosi, Bolivia

Field-hunting tip

Look in hydrothermal tin-silver veins country — that is the host setting where coiraite typically forms. If you start seeing cylindrite, franckeite, stannite in float, you are in the right ground. Field specimens usually show a platy crystals, tabular, striated habit, so train your eye for that shape before scanning the outcrop.

Common questions

How do you identify coiraite?+

Mohs hardness is 2.5. It typically shows a metallic luster. The streak is black. Common colors include black, lead-gray.

Where is coiraite found?+

Notable localities include Oruro Department, Bolivia; Cerro de Potosi, Bolivia.

How much is coiraite 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 coiraite safe to handle?+

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

What rocks look like coiraite?+

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

What minerals are found with coiraite?+

Coiraite commonly co-occurs with Cylindrite, Franckeite, Stannite, Galena. Spotting any of these in float or country rock is a useful trip signal.

What kind of rock does coiraite form in?+

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

What is coiraite used for?+

Coiraite is used in collector.

Find coiraite on the map

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