Costibite is a rare cobalt antimony sulfide often occurring as a component of hydrothermal veins alongside other cobalt minerals. It typically presents as metallic, tin-white massive aggregates that are difficult to distinguish from cobaltite without X-ray diffraction or chemical analysis.

Hardness

Mohs

Luster

Metallic

Streak

Black

Transparency

Opaque

mineralrare

Costibite

Hardness: 6
Luster: Metallic
Streak: Black
Transparency: Opaque

Is this costibite?

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 costibite with a known reference. Costibite sits at Mohs 6, 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: steel gray.
5
Look at form & habit
Crystal system: orthorhombic. Typical habit: inclusions, lamellar.

Often confused with

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

How to tell apart: Streak differs, so Costibite leaves black, Cobaltite leaves grayish black.

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Often found alongside costibite

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

All properties

Chemical formula: CoSbS
Mohs hardness: 6
Density: 6.89 g/cm³
Colors: Steel gray
Streak: Black
Luster: Metallic
Transparency: Opaque
Crystal system: Orthorhombic
Crystal habit: Inclusions, lamellar
Cleavage: None
Rarity: Rare
Uses: Collector
Host rock: Intimately intergrown with other hydrothermal sulfides (Broken Hill, Australia); in Pb–Zn–Cu–Ag ore deposits remobilized by hydrothermal solutions from later granite emplacement (Bergslagen, Sweden)

Where rockhounds find costibite

Classic worldwide localities

Consols mine, Broken Hill, New South Wales (type locality), Australia
Gruvåsen and Getön deposits, Bergslagen metallic province, Sweden
Sulitjelma, northern Norway

Field-hunting tip

Where it forms: Intimately intergrown with other hydrothermal sulfides (Broken Hill, Australia); in Pb–Zn–Cu–Ag ore deposits remobilized by hydrothermal solutions from later granite emplacement (Bergslagen, Sweden). If you start seeing löllingite, willyamite, dyscrasite in float, you are in the right ground. Typical habit: inclusions, lamellar. Train your eye for that shape before scanning the outcrop.

Common questions

How do you identify costibite?+

Mohs hardness is 6. Luster: metallic. The streak is black. Common colors include steel gray.

Where is costibite found?+

Notable localities include Consols mine, Broken Hill, New South Wales (type locality), Australia; Gruvåsen and Getön deposits, Bergslagen metallic province, Sweden; Sulitjelma, northern Norway.

Is costibite safe to handle?+

Costibite contains antimony and cobalt. Contains cobalt and antimony; wash hands thoroughly after handling and avoid inhaling dust when cutting or polishing.

What rocks look like costibite?+

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

What minerals are found with costibite?+

Costibite commonly co-occurs with Löllingite, Willyamite, Dyscrasite, Ullmannite, Pyrargyrite, Nisbite. Spotting any of these in float or country rock is a useful trip signal.

What kind of rock does costibite form in?+

Where it forms: Intimately intergrown with other hydrothermal sulfides (Broken Hill, Australia); in Pb–Zn–Cu–Ag ore deposits remobilized by hydrothermal solutions from later granite emplacement (Bergslagen, Sweden). Working float back to the host body is the standard way to chase a fresh occurrence.

What is costibite used for?+

Costibite is used in collector.

Find costibite on the map

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