Tiemannite is a rare mercury selenide mineral typically found as massive or granular aggregates within hydrothermal vein systems. It is characterized by its heavy weight, metallic luster, and black streak, often appearing alongside other selenium or mercury minerals.

Hardness

2.5

Mohs

Luster

Metallic

Streak

Nearly black

Transparency

Opaque

mineralrare

Tiemannite

Also: seleniomercurite

Hardness: 2.5
Luster: Metallic
Streak: Nearly black
Transparency: Opaque

Is this tiemannite?

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 tiemannite with a known reference. Tiemannite 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. Streak: nearly black.
3
Read the luster
Hold the specimen under a strong light. Luster: metallic.
4
Match the color range
Compare against the expected color range: gray, reddish brown, black.
5
Look at form & habit
Crystal system: cubic. Typical habit: euhedral crystals, massive.

Often confused with

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

mineral

Galena

Mohs 2.5-2.75

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

How to tell apart: Streak differs, so Tiemannite leaves nearly black, Tetrahedrite leaves black to brown.

Compare →

Often found alongside tiemannite

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

All properties

Chemical formula: HgSe
Mohs hardness: 2.5
Density: 8.19-8.47 g/cm³
Colors: Gray Reddish brown Black
Streak: Nearly black
Luster: Metallic
Transparency: Opaque
Crystal system: Cubic
Crystal habit: Euhedral crystals, massive
Cleavage: None
Rarity: Rare
Uses: Collector
Host rock: In hydrothermal veins with other selenides and calcite

Where rockhounds find tiemannite

Classic worldwide localities

Marysvale, Ohio district, Piute Co., Utah, USA
New Idria, San Benito Co., California, USA
Harz Mountains, from Clausthal (type locality), Tilkerode, Lerbach, and Zorge, Germany
Niederschlema, Saxony, Germany
Hope’s Nose, Torquay, Devon, England
Silver Glen, Alva, Scotland

Field-hunting tip

Where it forms: In hydrothermal veins with other selenides and calcite. If you start seeing clausthalite, eucairite, naumannite in float, you are in the right ground. Typical habit: euhedral crystals, massive. Train your eye for that shape before scanning the outcrop.

Common questions

How do you identify tiemannite?+

Mohs hardness is 2.5. Luster: metallic. The streak is nearly black. Common colors include gray, reddish brown, black.

Where is tiemannite found?+

Notable localities include Marysvale, Ohio district, Piute Co., Utah, USA; New Idria, San Benito Co., California, USA; Harz Mountains, from Clausthal (type locality), Tilkerode, Lerbach, and Zorge, Germany; Niederschlema, Saxony, Germany; Hope’s Nose, Torquay, Devon, England.

Is tiemannite safe to handle?+

Tiemannite contains mercury and selenium and calls for real care. Contains mercury and selenium. Handle with extreme care, do not inhale dust, and wash hands thoroughly after handling. Not suitable for casual handling or lapidary work.

What rocks look like tiemannite?+

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

What minerals are found with tiemannite?+

Tiemannite commonly co-occurs with Clausthalite, Eucairite, Naumannite, Klockmannite, Umangite, Metacinnabar. Spotting any of these in float or country rock is a useful trip signal.

What kind of rock does tiemannite form in?+

Where it forms: In hydrothermal veins with other selenides and calcite. Working float back to the host body is the standard way to chase a fresh occurrence.

What is tiemannite used for?+

Tiemannite is used in collector.

Find tiemannite on the map

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