Chrysothallite is a rare secondary mineral found in high-temperature fumaroles of volcanic systems. It typically occurs as delicate, bright green to yellow-green platy crystals or thin crusts associated with other exotic copper-bearing chlorides and selenites.

Hardness

Mohs

Luster

Vitreous

Streak

Pale Green

Transparency

Transparent

mineralrare

Chrysothallite

Hardness: 2
Luster: Vitreous
Streak: Pale Green
Transparency: Transparent

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Is this chrysothallite?

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 chrysothallite with a known reference. Chrysothallite 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. Chrysothallite leaves a pale green streak.
3
Read the luster
Hold the specimen under a strong light. Chrysothallite typically shows a vitreous luster.
4
Match the color range
Compare against the expected color range: green, yellow-green.
5
Look at form & habit
Crystal system: hexagonal. Typical habit: platy crystals, crusts.

Often confused with

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

mineral

Euchlorine

Mohs 3

How to tell apart: Euchlorine is the harder of the two (Mohs 3 vs. 2).

How to tell apart: Streak differs, so Chrysothallite leaves pale green, Chlorothionite leaves white.

Compare →

Often found alongside chrysothallite

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

All properties

Chemical formula: K₆Cu₆O₂Cl₁₀(SeO₃)₄
Mohs hardness: 2
Density: 4.26 g/cm³
Colors: Green Yellow-green
Streak: Pale Green
Luster: Vitreous
Transparency: Transparent
Crystal system: Hexagonal
Crystal habit: Platy Crystals, Crusts
Cleavage: Perfect
Rarity: Rare
Uses: Collector
Host rock: Fumarole Deposits

Where rockhounds find chrysothallite

Classic worldwide localities

Tolbachik volcano, Kamchatka Peninsula, Russia

Field-hunting tip

Look in fumarole deposits country, the host setting where chrysothallite typically forms. If you start seeing sylvite, halite, euchlorine in float, you are in the right ground. Field specimens usually show a platy crystals, crusts habit, so train your eye for that shape before scanning the outcrop.

Common questions

How do you identify chrysothallite?+

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

Where is chrysothallite found?+

Notable localities include Tolbachik volcano, Kamchatka Peninsula, Russia.

Is chrysothallite safe to handle?+

It contains toxic constituents. Contains copper and selenium; handle with care and avoid inhalation of dust or ingestion. Wash hands thoroughly after handling. Handle with care, avoid grinding or breathing dust, and store separately.

What rocks look like chrysothallite?+

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

What minerals are found with chrysothallite?+

Chrysothallite commonly co-occurs with Sylvite, Halite, Euchlorine, Chlorothionite. Spotting any of these in float or country rock is a useful trip signal.

What kind of rock does chrysothallite form in?+

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

What is chrysothallite used for?+

Chrysothallite is used in collector.

Find chrysothallite on the map

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