Andyrobertsite is an extremely rare arsenate mineral found almost exclusively in the oxidation zones of the Tsumeb Mine. It typically forms delicate, radiating clusters of electric blue or pale yellow crystals that are highly sought after by advanced systematic collectors.

Hardness

Mohs

Luster

Vitreous

Streak

Pale blue

Transparency

Transparent

mineralrare

Andyrobertsite

Hardness: 3
Luster: Vitreous
Streak: Pale blue
Transparency: Transparent

Is this andyrobertsite?

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 andyrobertsite with a known reference. Andyrobertsite 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: pale blue.
3
Read the luster
Hold the specimen under a strong light. Luster: vitreous.
4
Match the color range
Compare against the expected color range: electric blue.
5
Look at form & habit
Crystal system: monoclinic. Typical habit: platy.

Often confused with

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

mineral

Lavendulan

Mohs 2.5

How to tell apart: Streak differs, so Andyrobertsite leaves pale blue, Lavendulan leaves light blue.

How to tell apart: Andyrobertsite is noticeably harder (Mohs 3 vs. ~2).

Compare →

Often found alongside andyrobertsite

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

All properties

Chemical formula: KCdCu₅(AsO₄)₄[As(OH)₂O₂]·2H₂O
Mohs hardness: 3
Density: 4.011 g/cm³
Colors: Electric blue
Streak: Pale blue
Luster: Vitreous
Transparency: Transparent
Crystal system: Monoclinic
Crystal habit: Platy
Cleavage: Good on (100)
Rarity: Rare
Uses: Collector
Host rock: On a single specimen from a weathered polymetallic mineral deposit

Where rockhounds find andyrobertsite

Classic worldwide localities

Tsumeb mine, Namibia

Field-hunting tip

Where it forms: On a single specimen from a weathered polymetallic mineral deposit. If you start seeing cuprian adamite, zincian olivenite, calcioandyrobertsite in float, you are in the right ground. Typical habit: platy. Train your eye for that shape before scanning the outcrop.

Common questions

How do you identify andyrobertsite?+

Mohs hardness is 3. Luster: vitreous. The streak is pale blue. Common colors include electric blue.

Where is andyrobertsite found?+

Notable localities include Tsumeb mine, Namibia.

Is andyrobertsite safe to handle?+

Andyrobertsite contains arsenic, cadmium and copper and calls for real care. Contains arsenic and copper; avoid ingestion, inhalation of dust, and wash hands thoroughly after handling.

What rocks look like andyrobertsite?+

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

What minerals are found with andyrobertsite?+

Andyrobertsite commonly co-occurs with Cuprian adamite, Zincian olivenite, Calcioandyrobertsite, Tennantite. Spotting any of these in float or country rock is a useful trip signal.

What kind of rock does andyrobertsite form in?+

Where it forms: On a single specimen from a weathered polymetallic mineral deposit. Working float back to the host body is the standard way to chase a fresh occurrence.

What is andyrobertsite used for?+

Andyrobertsite is used in collector.

Find andyrobertsite on the map

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