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, 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.