Yancowinnaite is a rare lead copper aluminum arsenate that forms yellow to greenish yellow platy crystals in rosettes. It is a secondary mineral in the weathering zone of a Cu-Pb-Zn sulfide deposit. It was first described from Kintore open cut, Broken Hill, New South Wales, Australia.

Hardness

Mohs

Luster

Vitreous

Streak

Yellow

Transparency

Translucent

mineralrareTsumcorite Group family

Yancowinnaite

Hardness: ~3
Luster: Vitreous
Streak: Yellow
Transparency: Translucent

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Is this yancowinnaite?

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 yancowinnaite with a known reference. Yancowinnaite sits at Mohs ~3, softer than the next harder reference, harder than the previous one.
2
Check the streak
Drag the specimen across an unglazed porcelain plate. Streak: yellow.
3
Read the luster
Hold the specimen under a strong light. Luster: vitreous.
4
Match the color range
Compare against the expected color range: yellow, greenish yellow.
5
Look at form & habit
Crystal system: triclinic. Typical habit: platy crystals in rosette-like aggregates.

Often confused with

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

mineral

Tsumcorite

Mohs 4.5

How to tell apart: Tsumcorite is the harder of the two (Mohs 4.5 vs. ~3).

How to tell apart: Streak differs, so Yancowinnaite leaves yellow, Lavendulan leaves light blue.

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Often found alongside yancowinnaite

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

All properties

Chemical formula: PbCuAl(AsO₄)₂OH·H₂O
Mohs hardness: ~3
Density: 5.31 g/cm³
Colors: Yellow Greenish yellow
Streak: Yellow
Luster: Vitreous
Transparency: Translucent
Crystal system: Triclinic
Crystal habit: Platy crystals in rosette-like aggregates
Cleavage: One perfect on {111} (by analogy to gartrellite)
Rarity: Rare
Uses: Collector
Host rock: Secondary in the weathering zone of a Cu-Pb-Zn sulfide deposit

Where rockhounds find yancowinnaite

Classic worldwide localities

Kintore open cut, Broken Hill, New South Wales, Australia

Field-hunting tip

Where it forms: Secondary in the weathering zone of a Cu-Pb-Zn sulfide deposit. If you start seeing gartrellite, beudantite-segnitite, mimetite in float, you are in the right ground. Typical habit: platy crystals in rosette-like aggregates. Train your eye for that shape before scanning the outcrop.

Common questions

How do you identify yancowinnaite?+

Mohs hardness is ~3. Luster: vitreous. The streak is yellow. Common colors include yellow, greenish yellow.

Where is yancowinnaite found?+

Notable localities include Kintore open cut, Broken Hill, New South Wales, Australia.

Is yancowinnaite safe to handle?+

Yancowinnaite contains arsenic, copper and lead and calls for real care. Contains arsenic and lead, which are toxic if ingested or inhaled as dust. Wash hands thoroughly after handling and avoid creating dust.

What rocks look like yancowinnaite?+

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

What minerals are found with yancowinnaite?+

Yancowinnaite commonly co-occurs with Gartrellite, Beudantite-segnitite, Mimetite, Agardite-Y, Carminate, Chlorargyrite. Spotting any of these in float or country rock is a useful trip signal.

What kind of rock does yancowinnaite form in?+

Where it forms: Secondary in the weathering zone of a Cu-Pb-Zn sulfide deposit. Working float back to the host body is the standard way to chase a fresh occurrence.

What is yancowinnaite used for?+

Yancowinnaite is used in collector.

Find yancowinnaite on the map

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