Eugenite is a rare silver-mercury alloy belonging to the amalgam group. It typically occurs as small, [black] grains or masses within hydrothermal veins and is a significant mercury-bearing mineral for specialized collectors.

Hardness

2.5-3

Mohs

Luster

Metallic

Streak

Metallic

Transparency

Opaque

mineralrareAmalgam Group family

Eugenite

Hardness: 2.5-3
Luster: Metallic
Streak: Metallic
Transparency: Opaque

Is this eugenite?

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 eugenite with a known reference. Eugenite sits at Mohs 2.5-3, softer than the next harder reference, harder than the previous one.
2
Check the streak
Drag the specimen across an unglazed porcelain plate. Streak: metallic.
3
Read the luster
Hold the specimen under a strong light. Luster: metallic.
4
Match the color range
Compare against the expected color range: silver white.
5
Look at form & habit
Crystal system: cubic. Typical habit: grains, small masses.

Often confused with

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

mineral

Silver

Mohs 2.5-3

How to tell apart: Streak differs, so Eugenite leaves metallic, Silver leaves silver-white.

How to tell apart: Streak differs, so Eugenite leaves metallic, Dyscrasite leaves silver-white.

Compare →

Often found alongside eugenite

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

All properties

Chemical formula: Ag₁₁Hg₂
Mohs hardness: 2.5-3
Density: 10.75 g/cm³
Colors: Silver white
Streak: Metallic
Luster: Metallic
Transparency: Opaque
Crystal system: Cubic
Crystal habit: Grains, small masses
Cleavage: None
Rarity: Rare
Uses: Collector
Host rock: In low-grade copper sulfide ore in black shale and carbonate rocks (Lubin mine, Poland); in cuprite (Bisbee, Arizona, USA)

Where rockhounds find eugenite

Classic worldwide localities

Southwest mine, Bisbee, Cochise Co., Arizona, USA
Lubin (type locality) and Sieroszowice copper mines, near Legnica, Zechstein copper district, Lower Silesia, Poland

Field-hunting tip

Where it forms: In low-grade copper sulfide ore in black shale and carbonate rocks (Lubin mine, Poland); in cuprite (Bisbee, Arizona, USA). If you start seeing chalcocite, covellite, tennantite in float, you are in the right ground. Typical habit: grains, small masses. Train your eye for that shape before scanning the outcrop.

Common questions

How do you identify eugenite?+

Mohs hardness is 2.5-3. Luster: metallic. The streak is metallic. Common colors include silver white.

Where is eugenite found?+

Notable localities include Southwest mine, Bisbee, Cochise Co., Arizona, USA; Lubin (type locality) and Sieroszowice copper mines, near Legnica, Zechstein copper district, Lower Silesia, Poland.

Is eugenite safe to handle?+

Eugenite contains mercury and calls for real care. Contains mercury; handle with care, avoid inhalation of dust, wash hands after handling, and store in a sealed container.

What rocks look like eugenite?+

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

What minerals are found with eugenite?+

Eugenite commonly co-occurs with Chalcocite, Covellite, Tennantite, Hematite, Calcite, Ankerite. Spotting any of these in float or country rock is a useful trip signal.

What kind of rock does eugenite form in?+

Where it forms: In low-grade copper sulfide ore in black shale and carbonate rocks (Lubin mine, Poland); in cuprite (Bisbee, Arizona, USA). Working float back to the host body is the standard way to chase a fresh occurrence.

What is eugenite used for?+

Eugenite is used in collector.

Find eugenite on the map

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