Aleutite is an extremely rare copper arsenate mineral found as a result of volcanic fumarole activity. It typically occurs as tiny, dark, tabular crystals or crusts within specific high-temperature environments in the Kamchatka region.

Hardness

Mohs

Luster

Adamantine

Streak

Reddish black

Transparency

Transparent

mineralrare

Aleutite

Hardness: 2
Luster: Adamantine
Streak: Reddish black
Transparency: Transparent

No image

Is this aleutite?

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 aleutite with a known reference. Aleutite sits at Mohs 2, softer than the next harder reference, harder than the previous one.
2
Check the streak
Drag the specimen across an unglazed porcelain plate. Streak: reddish black.
3
Read the luster
Hold the specimen under a strong light. Luster: adamantine.
4
Match the color range
Compare against the expected color range: dark green, black.
5
Look at form & habit
Crystal system: monoclinic. Typical habit: tabular crystals, crusts.

Often confused with

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

mineral

Lammerite

Mohs 3-4

How to tell apart: Lammerite is the harder of the two (Mohs 3-4 vs. 2); luster reads adamantine on Aleutite and vitreous on Lammerite.

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Often found alongside aleutite

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

All properties

Chemical formula: [Cu₅O₂](AsO₄)(VO₄)·(Cu₀.₅☐₀.₅)Cl
Mohs hardness: 2
Density: 4.89 g/cm³
Colors: Dark green Black
Streak: Reddish black
Luster: Adamantine
Transparency: Transparent
Crystal system: Monoclinic
Crystal habit: Tabular crystals, crusts
Cleavage: None
Rarity: Rare
Uses: Collector
Host rock: fumarole deposits

Where rockhounds find aleutite

Classic worldwide localities

Tolbachik volcano, Kamchatka, Russia

Field-hunting tip

Where it forms: fumarole deposits. If you start seeing lammerite, tenorite, sylvite in float, you are in the right ground. Typical habit: tabular crystals, crusts. Train your eye for that shape before scanning the outcrop.

Common questions

How do you identify aleutite?+

Mohs hardness is 2. Luster: adamantine. The streak is reddish black. Common colors include dark green, black.

Where is aleutite found?+

Notable localities include Tolbachik volcano, Kamchatka, Russia.

Is aleutite safe to handle?+

Aleutite contains arsenic, copper and vanadium and calls for real care. Contains arsenic and copper; wash hands thoroughly after handling and avoid inhaling dust.

What rocks look like aleutite?+

Aleutite is most often confused with Lammerite. A quick hardness test and a streak check separate the look-alikes faster than color alone.

What minerals are found with aleutite?+

Aleutite commonly co-occurs with Lammerite, Tenorite, Sylvite, Halite. Spotting any of these in float or country rock is a useful trip signal.

What kind of rock does aleutite form in?+

Where it forms: fumarole deposits. Working float back to the host body is the standard way to chase a fresh occurrence.

What is aleutite used for?+

Aleutite is used in collector.

Find aleutite on the map

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