Evdokimovite is an exceptionally rare thallium-bearing sulfate mineral discovered in fumarole deposits of the Mutnovsky Volcano. It typically forms as small, vivid yellow crystalline crusts or aggregates, often associated with other rare volcanic sulfates. Due to its thallium content and exclusive occurrence in remote volcanic vents, it is highly sought after by specialized mineral collectors.

Hardness

Mohs

Luster

Vitreous

Streak

Yellow

Transparency

Transparent

mineralrare

Evdokimovite

Hardness: 2
Luster: Vitreous
Streak: Yellow
Transparency: Transparent

No image

Is this evdokimovite?

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 evdokimovite with a known reference. Evdokimovite 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. Evdokimovite leaves a yellow streak.
3
Read the luster
Hold the specimen under a strong light. Evdokimovite typically shows a vitreous luster.
4
Match the color range
Compare against the expected color range: yellow, orange-yellow.
5
Look at form & habit
Crystal system: triclinic. Typical habit: tabular crystals, crusts, aggregates.

Often confused with

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

Often found alongside evdokimovite

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

All properties

Chemical formula: K₄Tl₄(SO₄)₄
Mohs hardness: 2
Density: 2.8 g/cm³
Colors: Yellow Orange-yellow
Streak: Yellow
Luster: Vitreous
Transparency: Transparent
Crystal system: Triclinic
Crystal habit: Tabular Crystals, Crusts, Aggregates
Cleavage: None
Rarity: Rare
Uses: Collector
Host rock: Fumarole Deposits
Typical price: $100-500+ depending on matrix quality

Where rockhounds find evdokimovite

Classic worldwide localities

Mutnovsky Volcano, Kamchatka Peninsula, Russia

Field-hunting tip

Look in fumarole deposits country — that is the host setting where evdokimovite typically forms. If you start seeing thenardite, aphthitalite, krasheninnikovite in float, you are in the right ground. Field specimens usually show a tabular crystals, crusts, aggregates habit, so train your eye for that shape before scanning the outcrop.

Common questions

How do you identify evdokimovite?+

Mohs hardness is 2. It typically shows a vitreous luster. The streak is yellow. Common colors include yellow, orange-yellow.

Where is evdokimovite found?+

Notable localities include Mutnovsky Volcano, Kamchatka Peninsula, Russia.

How much is evdokimovite worth?+

Typical asking prices fall in the range of $100-500+ depending on matrix quality. Quality, size, and provenance can move individual specimens well outside that range.

Is evdokimovite safe to handle?+

It contains toxic constituents. Contains thallium, which is highly toxic. Handle with extreme care, avoid inhalation of dust, and wash hands thoroughly after contact. Handle with care, avoid grinding or breathing dust, and store separately.

What rocks look like evdokimovite?+

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

What minerals are found with evdokimovite?+

Evdokimovite commonly co-occurs with Thenardite, Aphthitalite, Krasheninnikovite. Spotting any of these in float or country rock is a useful trip signal.

What kind of rock does evdokimovite form in?+

Evdokimovite typically forms in fumarole deposits. Working float back to the host body is the standard way to chase a fresh occurrence.

What is evdokimovite used for?+

Evdokimovite is used in collector.

Find evdokimovite on the map

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