Hatchite is an extremely rare lead-thallium-arsenic sulfosalt primarily found in the famous Binn Valley of Switzerland. It typically occurs as small, metallic black tabular crystals within dolomitic marble, often closely associated with other complex arsenic-bearing minerals.

Hardness

3.5

Mohs

Luster

Metallic

Streak

Chocolate-brown

Transparency

Opaque to subtranslucent

mineralrareSulphosalt Group family

Hatchite

Hardness: 3.5
Luster: Metallic
Streak: Chocolate-brown
Transparency: Opaque to subtranslucent

Is this hatchite?

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 hatchite with a known reference. Hatchite sits at Mohs 3.5, softer than the next harder reference, harder than the previous one.
2
Check the streak
Drag the specimen across an unglazed porcelain plate. Streak: chocolate-brown.
3
Read the luster
Hold the specimen under a strong light. Luster: metallic.
4
Match the color range
Compare against the expected color range: lead gray, grayish black.
5
Look at form & habit
Crystal system: triclinic. Typical habit: euhedral crystals, microscopic crystals.

Often confused with

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

mineral

Gratonite

Mohs 2.5

How to tell apart: Hatchite is noticeably harder (Mohs 3.5 vs. 2.5); streak differs, so Hatchite leaves chocolate-brown, Gratonite leaves black.

Often found alongside hatchite

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

All properties

Chemical formula: AgPbTlAs₂S₅
Mohs hardness: 3.5
Density: 5.8 g/cm³
Colors: Lead gray Grayish black
Streak: Chocolate-brown
Luster: Metallic
Transparency: Opaque to subtranslucent
Crystal system: Triclinic
Crystal habit: Euhedral crystals, microscopic crystals
Cleavage: None observed
Rarity: Rare
Uses: Collector
Host rock: Of hydrothermal origin, in crystalline dolostone

Where rockhounds find hatchite

Classic worldwide localities

Lengenbach quarry, Binntal, Valais, Switzerland (type locality)

Field-hunting tip

Where it forms: Of hydrothermal origin, in crystalline dolostone. If you start seeing wallisite, hutchinsonite, jentschite in float, you are in the right ground. Typical habit: euhedral crystals, microscopic crystals. Train your eye for that shape before scanning the outcrop.

Common questions

How do you identify hatchite?+

Mohs hardness is 3.5. Luster: metallic. The streak is chocolate-brown. Common colors include lead gray, grayish black.

Where is hatchite found?+

Notable localities include Lengenbach quarry, Binntal, Valais, Switzerland (type locality).

Is hatchite safe to handle?+

Hatchite contains arsenic, lead and thallium and calls for real care. Contains lead, arsenic, and thallium, all of which are highly toxic; handle with extreme caution and wash hands thoroughly after contact.

What rocks look like hatchite?+

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

What minerals are found with hatchite?+

Hatchite commonly co-occurs with Wallisite, Hutchinsonite, Jentschite, Sicherite, Edenharterite, Bernardite. Spotting any of these in float or country rock is a useful trip signal.

What kind of rock does hatchite form in?+

Where it forms: Of hydrothermal origin, in crystalline dolostone. Working float back to the host body is the standard way to chase a fresh occurrence.

What is hatchite used for?+

Hatchite is used in collector.

Find hatchite on the map

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