Erzwiesite is an incredibly rare sulfosalt mineral primarily known from its type locality in the Gastein Valley of Austria. It typically occurs as small, metallic inclusions within quartz-rich hydrothermal veins associated with other lead and copper-bearing sulfides.

Hardness

3-3.5

Mohs

Luster

Metallic

Streak

Black

Transparency

Opaque

mineralrareSulfosalt family

Erzwiesite

Hardness: 3-3.5
Luster: Metallic
Streak: Black
Transparency: Opaque

Is this erzwiesite?

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 erzwiesite with a known reference. Erzwiesite sits at Mohs 3-3.5, softer than the next harder reference, harder than the previous one.
2
Check the streak
Drag the specimen across an unglazed porcelain plate. Streak: 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: lead-gray, black.
5
Look at form & habit
Crystal system: orthorhombic. Typical habit: anhedral grains, microscopic inclusions.

Often confused with

Erzwiesite 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 Erzwiesite leaves black, Galena leaves lead-gray.

How to tell apart: Streak differs, so Erzwiesite leaves black, Bismuthinite leaves lead-gray.

Compare →

Often found alongside erzwiesite

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

All properties

Chemical formula: Ag₈Pb₁₂Bi₁₆S₄₀
Mohs hardness: 3-3.5
Density: 6.08 g/cm³
Colors: Lead-gray Black
Streak: Black
Luster: Metallic
Transparency: Opaque
Crystal system: Orthorhombic
Crystal habit: Anhedral grains, microscopic inclusions
Cleavage: None observed
Rarity: Rare
Uses: Collector
Host rock: In hydrothermal vein type Ag-Pb-Zn deposits

Where rockhounds find erzwiesite

Classic worldwide localities

An unnamed prospect in the Erzwies mining district, Gastein Valley, Salzburg Province, Austria
Staročeské pásmo Lode (Old Bohemian Lode), Kutná Hora Ag-Pb-Zn ore district, 60 km east of Prague, Czech Republic

Field-hunting tip

Where it forms: In hydrothermal vein type Ag-Pb-Zn deposits. If you start seeing galena, quartz, chalcopyrite in float, you are in the right ground. Typical habit: anhedral grains, microscopic inclusions. Train your eye for that shape before scanning the outcrop.

Common questions

How do you identify erzwiesite?+

Mohs hardness is 3-3.5. Luster: metallic. The streak is black. Common colors include lead-gray, black.

Where is erzwiesite found?+

Notable localities include An unnamed prospect in the Erzwies mining district, Gastein Valley, Salzburg Province, Austria; Staročeské pásmo Lode (Old Bohemian Lode), Kutná Hora Ag-Pb-Zn ore district, 60 km east of Prague, Czech Republic.

Is erzwiesite safe to handle?+

Erzwiesite contains lead. Contains bismuth and lead, which are toxic if ingested or inhaled as dust. Wash hands thoroughly after handling and avoid creating dust.

What rocks look like erzwiesite?+

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

What minerals are found with erzwiesite?+

Erzwiesite commonly co-occurs with Galena, Quartz, Chalcopyrite, Pyrite. Spotting any of these in float or country rock is a useful trip signal.

What kind of rock does erzwiesite form in?+

Where it forms: In hydrothermal vein type Ag-Pb-Zn deposits. Working float back to the host body is the standard way to chase a fresh occurrence.

What is erzwiesite used for?+

Erzwiesite is used in collector.

Find erzwiesite on the map

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