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, so 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, 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.