Aleksite is a rare lead bismuth telluride-sulfide that typically forms as foliated, metallic-gray aggregates. Collectors usually find it as a minor constituent within hydrothermal gold-telluride vein systems, often intergrown with other bismuth tellurides.

Hardness

2.5

Mohs

Luster

Metallic

Streak

Pale green

Transparency

Opaque

mineralrareTetradymite Group family

Aleksite

Hardness: 2.5
Luster: Metallic
Streak: Pale green
Transparency: Opaque

Is this aleksite?

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 aleksite with a known reference. Aleksite 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: pale green.
3
Read the luster
Hold the specimen under a strong light. Luster: metallic.
4
Match the color range
Compare against the expected color range: steel gray.
5
Look at form & habit
Crystal system: trigonal. Typical habit: granular.

Often confused with

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

Often found alongside aleksite

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

All properties

Chemical formula: PbBi₂Te₂S₂
Mohs hardness: 2.5
Density: 7.57 g/cm³
Colors: Steel gray
Streak: Pale green
Luster: Metallic
Transparency: Opaque
Crystal system: Trigonal
Crystal habit: Granular
Cleavage: Perfect on {0001}
Rarity: Rare
Uses: Collector
Host rock: Of hydrothermal origin in sulfide-quartz veins (Alekseev mine, Russia)

Where rockhounds find aleksite

Classic worldwide localities

Tybo, Nye Co., Nevada, USA
Alekseev gold mine, Sutam district, Stanovoi Range, southeast Sakha, Russia (type locality)
San-notake district, Fukuoka Prefecture, Japan
St. David’s mine, Dolgellau district, Wales
Ardino deposit, Bulgaria
Barringer mine, Timmins, Ontario, Canada

Field-hunting tip

Where it forms: Of hydrothermal origin in sulfide-quartz veins (Alekseev mine, Russia). If you start seeing galena, gold, altaite in float, you are in the right ground. Typical habit: granular. Train your eye for that shape before scanning the outcrop.

Common questions

How do you identify aleksite?+

Mohs hardness is 2.5. Luster: metallic. The streak is pale green. Common colors include steel gray.

Where is aleksite found?+

Notable localities include Tybo, Nye Co., Nevada, USA; Alekseev gold mine, Sutam district, Stanovoi Range, southeast Sakha, Russia (type locality); San-notake district, Fukuoka Prefecture, Japan; St. David’s mine, Dolgellau district, Wales; Ardino deposit, Bulgaria.

Is aleksite safe to handle?+

Aleksite contains lead. Contains lead and tellurium; handle with care and avoid inhalation of dust or ingestion.

What rocks look like aleksite?+

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

What minerals are found with aleksite?+

Aleksite commonly co-occurs with Galena, Gold, Altaite, Tetradymite, Tsumoite, Rucklidgeite. Spotting any of these in float or country rock is a useful trip signal.

What kind of rock does aleksite form in?+

Where it forms: Of hydrothermal origin in sulfide-quartz veins (Alekseev mine, Russia). Working float back to the host body is the standard way to chase a fresh occurrence.

What is aleksite used for?+

Aleksite is used in collector.

Find aleksite on the map

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