Canosioite is an extremely rare arsenate mineral that occurs as small, vibrant yellow to orange-yellow crystals. It is primarily found in hydrothermal veins associated with specific lead and iron-rich deposits in the Italian Alps. Due to its rarity and specific chemical composition, it is highly sought after by advanced systematic mineral collectors.

Hardness

3.5

Mohs

Luster

Vitreous

Streak

Yellow

Transparency

Transparent

mineralrare

Canosioite

Hardness: 3.5
Luster: Vitreous
Streak: Yellow
Transparency: Transparent

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Is this canosioite?

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 canosioite with a known reference. Canosioite 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. Canosioite leaves a yellow streak.
3
Read the luster
Hold the specimen under a strong light. Canosioite typically shows a vitreous luster.
4
Match the color range
Compare against the expected color range: yellow, yellowish-orange.
5
Look at form & habit
Crystal system: orthorhombic. Typical habit: tabular crystals, subparallel aggregates.

Often confused with

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

mineral

Carminite

Mohs 3.5

How to tell apart: Streak differs — Canosioite leaves yellow, Carminite leaves yellowish-red.

How to tell apart: Streak differs — Canosioite leaves yellow, Duftite leaves light green.

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Often found alongside canosioite

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

All properties

Chemical formula: Pb₂Fe³⁺(AsO₄)₂(OH)
Mohs hardness: 3.5
Density: 4.57 g/cm³
Colors: Yellow Yellowish-orange
Streak: Yellow
Luster: Vitreous
Transparency: Transparent
Crystal system: Orthorhombic
Crystal habit: Tabular Crystals, Subparallel Aggregates
Cleavage: Perfect
Rarity: Rare
Uses: Collector
Host rock: Hydrothermal Veins in Metamorphic Rocks
Typical price: $100-500+ for micro-specimens

Where rockhounds find canosioite

Classic worldwide localities

Canosio, Piedmont, Italy

Field-hunting tip

Look in hydrothermal veins in metamorphic rocks country — that is the host setting where canosioite typically forms. If you start seeing quartz, goethite, beudantite in float, you are in the right ground. Field specimens usually show a tabular crystals, subparallel aggregates habit, so train your eye for that shape before scanning the outcrop.

Common questions

How do you identify canosioite?+

Mohs hardness is 3.5. It typically shows a vitreous luster. The streak is yellow. Common colors include yellow, yellowish-orange.

Where is canosioite found?+

Notable localities include Canosio, Piedmont, Italy.

How much is canosioite worth?+

Typical asking prices fall in the range of $100-500+ for micro-specimens. Quality, size, and provenance can move individual specimens well outside that range.

Is canosioite safe to handle?+

It contains toxic constituents. Contains arsenic and lead; handle with care and avoid inhalation of dust or ingestion. Handle with care, avoid grinding or breathing dust, and store separately.

What rocks look like canosioite?+

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

What minerals are found with canosioite?+

Canosioite commonly co-occurs with Quartz, Goethite, Beudantite. Spotting any of these in float or country rock is a useful trip signal.

What kind of rock does canosioite form in?+

Canosioite typically forms in hydrothermal veins in metamorphic rocks. Working float back to the host body is the standard way to chase a fresh occurrence.

What is canosioite used for?+

Canosioite is used in collector.

Find canosioite on the map

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