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

5-6

Mohs

Luster

Metallic

Streak

Black

Transparency

Opaque

mineralrare

Costibite

Hardness: 5-6
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 5-6 — softer than the next harder reference, harder than the previous one.
2
Check the streak
Drag the specimen across an unglazed porcelain plate. Costibite leaves a black streak.
3
Read the luster
Hold the specimen under a strong light. Costibite typically shows a metallic luster.
4
Match the color range
Compare against the expected color range: silver-white, tin-white.
5
Look at form & habit
Crystal system: orthorhombic. Typical habit: granular, massive, rare prismatic crystals.

Often confused with

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

How to tell apart: Streak differs — Costibite leaves black, Cobaltite leaves greyish-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: 5-6
Density: 7.5-7.7 g/cm³
Colors: Silver-white Tin-white
Streak: Black
Luster: Metallic
Transparency: Opaque
Crystal system: Orthorhombic
Crystal habit: Granular, Massive, Rare Prismatic Crystals
Cleavage: None
Rarity: Rare
Uses: Collector
Host rock: Hydrothermal Sulfide Veins
Typical price: $50-300 per specimen

Where rockhounds find costibite

Classic worldwide localities

Kobokobo, Democratic Republic of the Congo
Broken Hill, Australia
Cobalt, Ontario, Canada
Sweden

Field-hunting tip

Look in hydrothermal sulfide veins country — that is the host setting where costibite typically forms. If you start seeing cobaltite, gersdorffite, galena in float, you are in the right ground. Field specimens usually show a granular, massive, rare prismatic crystals habit, so train your eye for that shape before scanning the outcrop.

Common questions

How do you identify costibite?+

Mohs hardness is 5-6. It typically shows a metallic luster. The streak is black. Common colors include silver-white, tin-white.

Where is costibite found?+

Notable localities include Kobokobo, Democratic Republic of the Congo; Broken Hill, Australia; Cobalt, Ontario, Canada; Sweden.

How much is costibite 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 costibite safe to handle?+

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

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 Cobaltite, Gersdorffite, Galena, Chalcopyrite. Spotting any of these in float or country rock is a useful trip signal.

What kind of rock does costibite form in?+

Costibite typically forms in hydrothermal sulfide veins. 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.