Kalithallite is an extremely rare thallium-bearing halide mineral found in specific evaporite deposits. It typically forms as small, colorless to white octahedral crystals and is highly sensitive to humidity due to its water content.

Hardness

Mohs

Luster

Vitreous

Transparency

Transparent

mineralrare

Kalithallite

Hardness: 2
Luster: Vitreous
Transparency: Transparent

No image

Is this kalithallite?

4-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 kalithallite with a known reference. Kalithallite sits at Mohs 2, softer than the next harder reference, harder than the previous one.
2
Read the luster
Hold the specimen under a strong light. Luster: vitreous.
3
Match the color range
Compare against the expected color range: colorless, white.
4
Look at form & habit
Crystal system: tetragonal.

Often confused with

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

mineral

Carnallite

Mohs 2.5

How to tell apart: Luster reads vitreous on Kalithallite and greasy, shining on Carnallite.

Often found alongside kalithallite

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

All properties

Chemical formula: K₃TlCl₆·2H₂O
Mohs hardness: 2
Colors: Colorless White
Luster: Vitreous
Transparency: Transparent
Crystal system: Tetragonal
Rarity: Rare
Uses: Collector
Host rock: A sublimate at an active volcanic fumarole

Where rockhounds find kalithallite

Classic worldwide localities

Northern fumarole field, First scoria cone of the Northern Breakthrough of the Great Tolbachik Fissure Eruption, Tolbachik volcano, Kamchatka Peninsula, Far-Eastern Region, Russia

Field-hunting tip

Where it forms: A sublimate at an active volcanic fumarole. If you start seeing sylvite, carnallite, halite in float, you are in the right ground.

Common questions

How do you identify kalithallite?+

Mohs hardness is 2. Luster: vitreous. Common colors include colorless, white.

Where is kalithallite found?+

Notable localities include Northern fumarole field, First scoria cone of the Northern Breakthrough of the Great Tolbachik Fissure Eruption, Tolbachik volcano, Kamchatka Peninsula, Far-Eastern Region, Russia.

Is kalithallite safe to handle?+

Kalithallite contains thallium and calls for real care. Contains thallium, a highly toxic heavy metal. Handle with gloves, avoid dust inhalation, and wash hands thoroughly after contact.

What rocks look like kalithallite?+

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

What minerals are found with kalithallite?+

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

What kind of rock does kalithallite form in?+

Where it forms: A sublimate at an active volcanic fumarole. Working float back to the host body is the standard way to chase a fresh occurrence.

What is kalithallite used for?+

Kalithallite is used in collector.

Find kalithallite on the map

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