Colusite is a rare copper-vanadium-arsenic sulfosalt often found as fine-grained masses within hydrothermal copper ore deposits. It is best identified in polished section under reflected light by its distinctive bronze-brown color and association with other complex sulfides.

Hardness

3-4

Mohs

Luster

Metallic

Streak

Black

Transparency

Opaque

mineralrareGermanite Group family

Colusite

Hardness: 3-4
Luster: Metallic
Streak: Black
Transparency: Opaque

Is this colusite?

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 colusite with a known reference. Colusite sits at Mohs 3-4 — softer than the next harder reference, harder than the previous one.
2
Check the streak
Drag the specimen across an unglazed porcelain plate. Colusite leaves a black streak.
3
Read the luster
Hold the specimen under a strong light. Colusite typically shows a metallic luster.
4
Match the color range
Compare against the expected color range: bronze-brown, dark gray, brass-yellow.
5
Look at form & habit
Crystal system: cubic. Typical habit: massive, granular, rarely as small tetrahedral crystals.

Often confused with

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

mineral

Enargite

Mohs 3

How to tell apart: Streak differs — Colusite leaves black, Enargite leaves grayish-black.

Often found alongside colusite

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

All properties

Chemical formula: Cu₂₆V₂As₆S₃₂
Mohs hardness: 3-4
Density: 4.5-4.6 g/cm³
Colors: Bronze-brown Dark Gray Brass-yellow
Streak: Black
Luster: Metallic
Transparency: Opaque
Crystal system: Cubic
Crystal habit: Massive, Granular, Rarely as Small Tetrahedral Crystals
Cleavage: None
Rarity: Rare
Uses: Collector, Scientific Research
Host rock: Hydrothermal Copper-arsenic Deposits
Typical price: $20-150 depending on size and association

Where rockhounds find colusite

Classic worldwide localities

Butte, Montana (USA)
Bor, Serbia
Tsumeb, Namibia
Srednogorie, Bulgaria

Field-hunting tip

Look in hydrothermal copper-arsenic deposits country — that is the host setting where colusite typically forms. If you start seeing enargite, tennantite, pyrite in float, you are in the right ground. Field specimens usually show a massive, granular, rarely as small tetrahedral crystals habit, so train your eye for that shape before scanning the outcrop.

Common questions

How do you identify colusite?+

Mohs hardness is 3-4. It typically shows a metallic luster. The streak is black. Common colors include bronze-brown, dark gray, brass-yellow.

Where is colusite found?+

Notable localities include Butte, Montana (USA); Bor, Serbia; Tsumeb, Namibia; Srednogorie, Bulgaria.

How much is colusite worth?+

Typical asking prices fall in the range of $20-150 depending on size and association. Quality, size, and provenance can move individual specimens well outside that range.

Is colusite safe to handle?+

It contains toxic constituents. Contains arsenic and copper; avoid ingestion, inhalation of dust, and wash hands thoroughly after handling. Handle with care, avoid grinding or breathing dust, and store separately.

What rocks look like colusite?+

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

What minerals are found with colusite?+

Colusite commonly co-occurs with Enargite, Tennantite, Pyrite, Bornite, Sphalerite. Spotting any of these in float or country rock is a useful trip signal.

What kind of rock does colusite form in?+

Colusite typically forms in hydrothermal copper-arsenic deposits. Working float back to the host body is the standard way to chase a fresh occurrence.

What is colusite used for?+

Colusite is used in collector, scientific research.

Find colusite on the map

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