Finnemanite is a rare lead arsenite chloride mineral found almost exclusively in the historic Langban mines of Sweden. It is highly sought after by collectors for its brilliant adamantine luster and well-defined, hexagonal prismatic crystal habits.

Hardness

2.5-3

Mohs

Luster

Adamantine

Streak

White

Transparency

Transparent

mineralrare

Finnemanite

Hardness: 2.5-3
Luster: Adamantine
Streak: White
Transparency: Transparent

Is this finnemanite?

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 finnemanite with a known reference. Finnemanite sits at Mohs 2.5-3 — softer than the next harder reference, harder than the previous one.
2
Check the streak
Drag the specimen across an unglazed porcelain plate. Finnemanite leaves a white streak.
3
Read the luster
Hold the specimen under a strong light. Finnemanite typically shows a adamantine luster.
4
Match the color range
Compare against the expected color range: gray, white, colorless, yellowish-white.
5
Look at form & habit
Crystal system: hexagonal. Typical habit: prismatic crystals, often with pyramidal terminations.

Often confused with

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

How to tell apart: Luster reads adamantine on Finnemanite and resinous on Pyromorphite.

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Often found alongside finnemanite

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

All properties

Chemical formula: Pb₅(AsO₃)₃Cl
Mohs hardness: 2.5-3
Density: 7.1 g/cm³
Colors: Gray White Colorless Yellowish-white
Streak: White
Luster: Adamantine
Transparency: Transparent
Crystal system: Hexagonal
Crystal habit: Prismatic Crystals, Often with Pyramidal Terminations
Cleavage: Distinct On {1010}
Rarity: Rare
Uses: Collector
Host rock: Manganese-rich Skarn Deposits
Typical price: $50-300 thumbnail

Where rockhounds find finnemanite

Classic worldwide localities

Langban, Sweden

Field-hunting tip

Look in manganese-rich skarn deposits country — that is the host setting where finnemanite typically forms. If you start seeing barite, hausmannite, manganosite in float, you are in the right ground. Field specimens usually show a prismatic crystals, often with pyramidal terminations habit, so train your eye for that shape before scanning the outcrop.

Common questions

How do you identify finnemanite?+

Mohs hardness is 2.5-3. It typically shows a adamantine luster. The streak is white. Common colors include gray, white, colorless, yellowish-white.

Where is finnemanite found?+

Notable localities include Langban, Sweden.

How much is finnemanite worth?+

Typical asking prices fall in the range of $50-300 thumbnail. Quality, size, and provenance can move individual specimens well outside that range.

Is finnemanite safe to handle?+

It contains toxic constituents. Contains lead and arsenic; avoid inhalation of dust and wash hands thoroughly after handling. Handle with care, avoid grinding or breathing dust, and store separately.

What rocks look like finnemanite?+

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

What minerals are found with finnemanite?+

Finnemanite commonly co-occurs with Barite, Hausmannite, Manganosite, Galena. Spotting any of these in float or country rock is a useful trip signal.

What kind of rock does finnemanite form in?+

Finnemanite typically forms in manganese-rich skarn deposits. Working float back to the host body is the standard way to chase a fresh occurrence.

What is finnemanite used for?+

Finnemanite is used in collector.

Find finnemanite on the map

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