Gortdrumite is an exceptionally rare copper-mercury sulfide mineral first identified in the Gortdrum mine in Ireland. It is typically found as microscopic grains or small aggregates within copper sulfide ores, making it a prized discovery for systematic mineral collectors.

Hardness

3.5

Mohs

Luster

Metallic

Streak

Black

Transparency

Opaque

mineralrare

Gortdrumite

Hardness: 3.5
Luster: Metallic
Streak: Black
Transparency: Opaque

Is this gortdrumite?

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 gortdrumite with a known reference. Gortdrumite sits at Mohs 3.5 — softer than the next harder reference, harder than the previous one.
2
Check the streak
Drag the specimen across an unglazed porcelain plate. Gortdrumite leaves a black streak.
3
Read the luster
Hold the specimen under a strong light. Gortdrumite typically shows a metallic luster.
4
Match the color range
Compare against the expected color range: black, brown.
5
Look at form & habit
Crystal system: orthorhombic. Typical habit: granular aggregates, massive.

Often confused with

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

Often found alongside gortdrumite

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

All properties

Chemical formula: (Cu,Fe)₆Hg₂S₅
Mohs hardness: 3.5
Density: 4.74 g/cm³
Colors: Black Brown
Streak: Black
Luster: Metallic
Transparency: Opaque
Crystal system: Orthorhombic
Crystal habit: Granular Aggregates, Massive
Cleavage: None
Rarity: Rare
Uses: Collector
Host rock: Dolomitized Limestone in Hydrothermal Deposits
Typical price: $50-300 per specimen

Where rockhounds find gortdrumite

Classic worldwide localities

Gortdrum mine, Tipperary, Ireland

Field-hunting tip

Look in dolomitized limestone in hydrothermal deposits country — that is the host setting where gortdrumite typically forms. If you start seeing bornite, chalcopyrite, tennantite in float, you are in the right ground. Field specimens usually show a granular aggregates, massive habit, so train your eye for that shape before scanning the outcrop.

Common questions

How do you identify gortdrumite?+

Mohs hardness is 3.5. It typically shows a metallic luster. The streak is black. Common colors include black, brown.

Where is gortdrumite found?+

Notable localities include Gortdrum mine, Tipperary, Ireland.

How much is gortdrumite 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 gortdrumite safe to handle?+

It contains toxic constituents. Contains mercury and copper; handle with care and wash hands thoroughly after handling. Do not inhale dust. Handle with care, avoid grinding or breathing dust, and store separately.

What rocks look like gortdrumite?+

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

What minerals are found with gortdrumite?+

Gortdrumite commonly co-occurs with bornite, chalcopyrite, tennantite, barite, calcite. Spotting any of these in float or country rock is a useful trip signal.

What kind of rock does gortdrumite form in?+

Gortdrumite typically forms in dolomitized limestone in hydrothermal deposits. Working float back to the host body is the standard way to chase a fresh occurrence.

What is gortdrumite used for?+

Gortdrumite is used in collector.

Find gortdrumite on the map

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