Laurionite is a rare lead halide mineral famously associated with the ancient slag heaps of Laurium, Greece. It typically forms as delicate, colorless to white prismatic crystals in oxidized lead environments, often appearing in association with other lead minerals like cerussite.

Hardness

3-3.5

Mohs

Luster

Adamantine, pearly on {100}

Streak

White

Transparency

Transparent

mineralrare

Laurionite

Hardness: 3-3.5
Luster: Adamantine, pearly on {100}
Streak: White
Transparency: Transparent

Is this laurionite?

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 laurionite with a known reference. Laurionite sits at Mohs 3-3.5, softer than the next harder reference, harder than the previous one.
2
Check the streak
Drag the specimen across an unglazed porcelain plate. Streak: white.
3
Read the luster
Hold the specimen under a strong light. Luster: adamantine, pearly on {100}.
4
Match the color range
Compare against the expected color range: colorless, white.
5
Look at form & habit
Crystal system: orthorhombic. Typical habit: crystalline, prismatic.

Often confused with

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

Often found alongside laurionite

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

All properties

Chemical formula: PbCl(OH)
Mohs hardness: 3-3.5
Density: 6.241 g/cm³
Colors: Colorless White
Streak: White
Luster: Adamantine, pearly on {100}
Transparency: Transparent
Crystal system: Orthorhombic
Crystal habit: Crystalline, prismatic
Cleavage: {101}, distinct
Rarity: Rare
Uses: Collector
Host rock: Produced by the action of saline water on lead-bearing slag

Where rockhounds find laurionite

Classic worldwide localities

Minnamax Cu–Ni sulfide deposit, Duluth Gabbro complex, near Hibbing, St. Louis Co., Minnesota, USA
Laurium, Greece
Baratti Beach, Tuscany, Italy
Juliushütte, Astfeld, Harz Mountains, Germany
Argent Pb–Zn mines, about 100 km east of Johannesburg, Transvaal, South Africa
Mineral deposits at: Wheal Rose, near Sithney, Cornwall, and the Wesley mine, near Higher Pitts, Somerset, England

Field-hunting tip

Where it forms: Produced by the action of saline water on lead-bearing slag. If you start seeing paralaurionite, penfieldite, fiedlerite in float, you are in the right ground. Typical habit: crystalline, prismatic. Train your eye for that shape before scanning the outcrop.

Common questions

How do you identify laurionite?+

Mohs hardness is 3-3.5. Luster: adamantine, pearly on {100}. The streak is white. Common colors include colorless, white.

Where is laurionite found?+

Notable localities include Minnamax Cu–Ni sulfide deposit, Duluth Gabbro complex, near Hibbing, St. Louis Co., Minnesota, USA; Laurium, Greece; Baratti Beach, Tuscany, Italy; Juliushütte, Astfeld, Harz Mountains, Germany; Argent Pb–Zn mines, about 100 km east of Johannesburg, Transvaal, South Africa.

Is laurionite safe to handle?+

Laurionite contains lead. Contains lead, which is toxic if ingested or inhaled as dust. Wash hands thoroughly after handling and avoid creating dust when cleaning specimens.

What rocks look like laurionite?+

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

What minerals are found with laurionite?+

Laurionite commonly co-occurs with Paralaurionite, Penfieldite, Fiedlerite, Phosgenite, Cerussite, Anglesite. Spotting any of these in float or country rock is a useful trip signal.

What kind of rock does laurionite form in?+

Where it forms: Produced by the action of saline water on lead-bearing slag. Working float back to the host body is the standard way to chase a fresh occurrence.

What is laurionite used for?+

Laurionite is used in collector.

Find laurionite on the map

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