Keutschite is a rare mercury-bearing sulfosalt belonging to the tetrahedrite group. It typically occurs as small metallic tetrahedral crystals in hydrothermal mineral deposits and is primarily sought after by advanced systematic collectors.

Hardness

3-4

Mohs

Luster

Metallic

Streak

Black

Transparency

Opaque

mineralrareTetrahedrite Group family

Keutschite

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

Is this keutschite?

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 keutschite with a known reference. Keutschite 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. Keutschite leaves a black streak.
3
Read the luster
Hold the specimen under a strong light. Keutschite typically shows a metallic luster.
4
Match the color range
Compare against the expected color range: gray, black.
5
Look at form & habit
Crystal system: cubic. Typical habit: tetrahedral.

Often confused with

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

How to tell apart: Streak differs — Keutschite leaves black, Cinnabar leaves scarlet; luster reads metallic on Keutschite and adamantine on Cinnabar.

Compare →

Often found alongside keutschite

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

All properties

Chemical formula: Cu₁₂Hg₂As₄S₁₃
Mohs hardness: 3-4
Density: 4.9-5.1 g/cm³
Colors: Gray Black
Streak: Black
Luster: Metallic
Transparency: Opaque
Crystal system: Cubic
Crystal habit: Tetrahedral
Cleavage: None
Rarity: Rare
Uses: Collector
Host rock: Hydrothermal Veins
Typical price: $100-500 thumbnail

Where rockhounds find keutschite

Classic worldwide localities

Keutschach, Austria
Rudabánya, Hungary

Field-hunting tip

Look in hydrothermal veins country — that is the host setting where keutschite typically forms. If you start seeing cinnabar, tetrahedrite, dolomite in float, you are in the right ground. Field specimens usually show a tetrahedral habit, so train your eye for that shape before scanning the outcrop.

Common questions

How do you identify keutschite?+

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

Where is keutschite found?+

Notable localities include Keutschach, Austria; Rudabánya, Hungary.

How much is keutschite worth?+

Typical asking prices fall in the range of $100-500 thumbnail. Quality, size, and provenance can move individual specimens well outside that range.

Is keutschite safe to handle?+

It contains toxic constituents. Contains mercury and arsenic; handle with care and avoid inhalation of dust or ingestion. Handle with care, avoid grinding or breathing dust, and store separately.

What rocks look like keutschite?+

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

What minerals are found with keutschite?+

Keutschite commonly co-occurs with Cinnabar, Tetrahedrite, Dolomite. Spotting any of these in float or country rock is a useful trip signal.

What kind of rock does keutschite form in?+

Keutschite typically forms in hydrothermal veins. Working float back to the host body is the standard way to chase a fresh occurrence.

What is keutschite used for?+

Keutschite is used in collector.

Find keutschite on the map

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