Ustarasite is a rare lead bismuth sulfide mineral typically found in complex hydrothermal deposits. It is best identified through laboratory analysis as it visually resembles several other lead-bismuth sulfosalts, typically appearing as massive metallic gray aggregates.

Hardness

2.5

Mohs

Luster

Metallic

Streak

Black

Transparency

Opaque

mineralrare

Ustarasite

Hardness: 2.5
Luster: Metallic
Streak: Black
Transparency: Opaque

Is this ustarasite?

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 ustarasite with a known reference. Ustarasite 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: 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, silver gray.
5
Look at form & habit
Crystal system: orthorhombic. Typical habit: prismatic.

Often confused with

Ustarasite 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 Ustarasite leaves black, Galena leaves lead-gray.

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

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Often found alongside ustarasite

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

All properties

Chemical formula: Pb(Bi,Sb)₆S₁₀
Mohs hardness: 2.5
Density: 6.8 g/cm³
Colors: Gray Silver gray
Streak: Black
Luster: Metallic
Transparency: Opaque
Crystal system: Orthorhombic
Crystal habit: Prismatic
Cleavage: One perfect; another present
Rarity: Rare
Uses: Collector
Host rock: In quartz-bismuthinite veins (Ustarasai deposit, Uzbekistan)

Where rockhounds find ustarasite

Classic worldwide localities

Ustarasai bismuth deposit, near Brichmulla, Pskem Mountains, southern Tien-Shan, northeastern Uzbekistan (type locality)
Pangushan tungsten deposit, Huang sha district, Jiangxi Province, China

Field-hunting tip

Where it forms: In quartz-bismuthinite veins (Ustarasai deposit, Uzbekistan). If you start seeing bismuthinite, kobellite, bismuthian jamesonite in float, you are in the right ground. Typical habit: prismatic. Train your eye for that shape before scanning the outcrop.

Common questions

How do you identify ustarasite?+

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

Where is ustarasite found?+

Notable localities include Ustarasai bismuth deposit, near Brichmulla, Pskem Mountains, southern Tien-Shan, northeastern Uzbekistan (type locality); Pangushan tungsten deposit, Huang sha district, Jiangxi Province, China.

Is ustarasite safe to handle?+

Ustarasite contains antimony and lead. Contains lead and bismuth; wash hands thoroughly after handling and avoid inhaling dust or ingesting.

What rocks look like ustarasite?+

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

What minerals are found with ustarasite?+

Ustarasite commonly co-occurs with Bismuthinite, Kobellite, Bismuthian jamesonite, Quartz. Spotting any of these in float or country rock is a useful trip signal.

What kind of rock does ustarasite form in?+

Where it forms: In quartz-bismuthinite veins (Ustarasai deposit, Uzbekistan). Working float back to the host body is the standard way to chase a fresh occurrence.

What is ustarasite used for?+

Ustarasite is used in collector.

Find ustarasite on the map

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