Camgasite is a very rare hydrated calcium magnesium arsenate that typically forms delicate, radiating clusters of acicular crystals. It is primarily found in the oxidized zones of arsenic-rich base metal deposits, notably in the historic mining district of Lavrion, Greece. Due to its arsenic content and limited occurrence, it is highly sought after by systematic mineral collectors.

Hardness

Mohs

Luster

Vitreous

Streak

White

Transparency

Transparent to translucent

mineralrare

Camgasite

Hardness: ~2
Luster: Vitreous
Streak: White
Transparency: Transparent to translucent

No image

Is this camgasite?

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 camgasite with a known reference. Camgasite sits at Mohs ~2, 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: vitreous.
4
Match the color range
Compare against the expected color range: colorless.
5
Look at form & habit
Crystal system: monoclinic. Typical habit: acicular crystals, radiating sprays.

Often confused with

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

mineral

Picropharmacolite

Mohs 1.5-2

How to tell apart: Luster reads vitreous on Camgasite and feeble pearly to silky on Picropharmacolite.

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Often found alongside camgasite

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

All properties

Chemical formula: CaMg(AsO₄)(OH)·5H₂O
Mohs hardness: ~2
Density: 2.4 g/cm³
Colors: Colorless
Streak: White
Luster: Vitreous
Transparency: Transparent to translucent
Crystal system: Monoclinic
Crystal habit: Acicular crystals, radiating sprays
Cleavage: {100}, {001}, distinct
Rarity: Rare
Uses: Collector
Host rock: A secondary mineral in a Co–U-rich zone in a polymetallic mineral deposit

Where rockhounds find camgasite

Classic worldwide localities

Johann mine, near Wittichen, Black Forest, Germany

Field-hunting tip

Where it forms: A secondary mineral in a Co–U-rich zone in a polymetallic mineral deposit. If you start seeing monohydrocalcite, gypsum, calcite in float, you are in the right ground. Typical habit: acicular crystals, radiating sprays. Train your eye for that shape before scanning the outcrop.

Common questions

How do you identify camgasite?+

Mohs hardness is ~2. Luster: vitreous. The streak is white. Common colors include colorless.

Where is camgasite found?+

Notable localities include Johann mine, near Wittichen, Black Forest, Germany.

Is camgasite safe to handle?+

Camgasite contains arsenic and calls for real care. Contains arsenic. Handle with care, wash hands after touching, and avoid inhalation of dust or ingestion.

What rocks look like camgasite?+

Camgasite is most often confused with Picropharmacolite. A quick hardness test and a streak check separate the look-alikes faster than color alone.

What minerals are found with camgasite?+

Camgasite commonly co-occurs with Monohydrocalcite, Gypsum, Calcite, Rapidcreekite, Nováčekite, Erythrite. Spotting any of these in float or country rock is a useful trip signal.

What kind of rock does camgasite form in?+

Where it forms: A secondary mineral in a Co–U-rich zone in a polymetallic mineral deposit. Working float back to the host body is the standard way to chase a fresh occurrence.

What is camgasite used for?+

Camgasite is used in collector.

Find camgasite on the map

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