Arcubisite is an extremely rare silver-copper-bismuth sulfosalt mineral found almost exclusively in the Ilimaussaq alkaline complex of Greenland. It typically occurs as microscopic inclusions within other sulfide minerals, making it a challenging find for even advanced collectors.

Hardness

2.5

Mohs

Luster

Metallic

Streak

Black

Transparency

Opaque

mineralrare

Arcubisite

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

Is this arcubisite?

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 arcubisite with a known reference. Arcubisite 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. Arcubisite leaves a black streak.
3
Read the luster
Hold the specimen under a strong light. Arcubisite typically shows a metallic luster.
4
Match the color range
Compare against the expected color range: lead-gray, silver-white.
5
Look at form & habit
Crystal system: orthorhombic. Typical habit: anhedral grains.

Often confused with

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

mineral

Galena

Mohs 2.5

How to tell apart: Streak differs, so Arcubisite leaves black, Galena leaves lead-gray.

How to tell apart: Streak differs, so Arcubisite leaves black, Aikinite leaves lead-gray.

Compare →

Often found alongside arcubisite

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

All properties

Chemical formula: Ag₆CuBiS₄
Mohs hardness: 2.5
Density: 7.98 g/cm³
Colors: Lead-gray Silver-white
Streak: Black
Luster: Metallic
Transparency: Opaque
Crystal system: Orthorhombic
Crystal habit: Anhedral Grains
Cleavage: None
Rarity: Rare
Uses: Collector
Host rock: Alkaline Igneous Rocks
Typical price: Expensive, primarily found in specialized mineral collections.

Where rockhounds find arcubisite

Classic worldwide localities

Ilimaussaq Complex, Greenland

Field-hunting tip

Look in alkaline igneous rocks country, the host setting where arcubisite typically forms. If you start seeing chalcocite, galena, sphalerite in float, you are in the right ground. Field specimens usually show a anhedral grains habit, so train your eye for that shape before scanning the outcrop.

Common questions

How do you identify arcubisite?+

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

Where is arcubisite found?+

Notable localities include Ilimaussaq Complex, Greenland.

How much is arcubisite worth?+

Typical asking prices fall in the range of Expensive, primarily found in specialized mineral collections.. Quality, size, and provenance can move individual specimens well outside that range.

Is arcubisite safe to handle?+

It contains toxic constituents. Contains silver, copper, and bismuth, but the primary concern is the presence of sulfur and heavy metals. Handle with care and wash hands after touching, as it may release harmful substances if powdered or heated. Handle with care, avoid grinding or breathing dust, and store separately.

What rocks look like arcubisite?+

Arcubisite is most often confused with Galena, Argentite, Aikinite. A quick hardness test and a streak check separate the look-alikes faster than color alone.

What minerals are found with arcubisite?+

Arcubisite commonly co-occurs with chalcocite, galena, sphalerite, argentite. Spotting any of these in float or country rock is a useful trip signal.

What kind of rock does arcubisite form in?+

Arcubisite typically forms in alkaline igneous rocks. Working float back to the host body is the standard way to chase a fresh occurrence.

What is arcubisite used for?+

Arcubisite is used in collector.

Find arcubisite on the map

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