Geigerite is a very rare manganese arsenate mineral typically found as small, pearly, platy crystals. It is primarily known from the historic manganese mines of Langban, Sweden, often occurring in association with other rare manganese species.

Hardness

3-4

Mohs

Luster

Pearly

Streak

White

Transparency

Transparent

mineralrareNone family

Geigerite

Hardness: 3-4
Luster: Pearly
Streak: White
Transparency: Transparent

No image

Is this geigerite?

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 geigerite with a known reference. Geigerite sits at Mohs 3-4 — softer than the next harder reference, harder than the previous one.
2
Check the streak
Drag the specimen across an unglazed porcelain plate. Geigerite leaves a white streak.
3
Read the luster
Hold the specimen under a strong light. Geigerite typically shows a pearly luster.
4
Match the color range
Compare against the expected color range: colorless, white, pale pink.
5
Look at form & habit
Crystal system: triclinic. Typical habit: platy crystals.

Often confused with

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

mineral

Heulandite

Mohs 3.5-4

How to tell apart: Luster reads pearly on Geigerite and vitreous to pearly on Heulandite.

How to tell apart: Luster reads pearly on Geigerite and vitreous on Stilbite.

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Often found alongside geigerite

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

All properties

Chemical formula: Mn₅(AsO₄)₂·10H₂O
Mohs hardness: 3-4
Density: 2.16 g/cm³
Colors: Colorless White Pale Pink
Streak: White
Luster: Pearly
Transparency: Transparent
Crystal system: Triclinic
Crystal habit: Platy Crystals
Cleavage: Perfect On {001}
Rarity: Rare
Uses: Collector
Host rock: Manganese Ore Deposits
Typical price: $50-300 per specimen

Where rockhounds find geigerite

Classic worldwide localities

Langban, Sweden

Field-hunting tip

Look in manganese ore deposits country — that is the host setting where geigerite typically forms. If you start seeing hausmannite, rhodo-chrosite, barite in float, you are in the right ground. Field specimens usually show a platy crystals habit, so train your eye for that shape before scanning the outcrop.

Common questions

How do you identify geigerite?+

Mohs hardness is 3-4. It typically shows a pearly luster. The streak is white. Common colors include colorless, white, pale pink.

Where is geigerite found?+

Notable localities include Langban, Sweden.

How much is geigerite worth?+

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

Is geigerite safe to handle?+

It contains toxic constituents. Contains arsenic, which is toxic if ingested or inhaled as dust. Handle with care and wash hands thoroughly after handling. Handle with care, avoid grinding or breathing dust, and store separately.

What rocks look like geigerite?+

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

What minerals are found with geigerite?+

Geigerite commonly co-occurs with Hausmannite, Rhodo-chrosite, Barite. Spotting any of these in float or country rock is a useful trip signal.

What kind of rock does geigerite form in?+

Geigerite typically forms in manganese ore deposits. Working float back to the host body is the standard way to chase a fresh occurrence.

What is geigerite used for?+

Geigerite is used in collector.

Find geigerite on the map

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