Calcioandyrobertsite is an extremely rare arsenate mineral characterized by its delicate bladed crystal habits and pale blue coloration. It is primarily found in the secondary oxidation zones of complex hydrothermal arsenic-bearing deposits, most notably associated with the world-famous Tsumeb Mine. It is a highly sought-after species for advanced collectors of rare arsenate minerals due to its complex crystal structure and scarcity.

Hardness

Mohs

Luster

Vitreous

Streak

White

Transparency

Translucent

mineralrareAndyrobertsite-Calcioandyrobertsite Series family

Calcioandyrobertsite

Hardness: 3
Luster: Vitreous
Streak: White
Transparency: Translucent

Is this calcioandyrobertsite?

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 calcioandyrobertsite with a known reference. Calcioandyrobertsite 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. Calcioandyrobertsite leaves a white streak.
3
Read the luster
Hold the specimen under a strong light. Calcioandyrobertsite typically shows a vitreous luster.
4
Match the color range
Compare against the expected color range: pale blue, white, colorless.
5
Look at form & habit
Crystal system: monoclinic. Typical habit: bladed crystals, radial aggregates.

Often confused with

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

How to tell apart: Streak differs — Calcioandyrobertsite leaves white, Cornubite leaves pale green.

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Often found alongside calcioandyrobertsite

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

All properties

Chemical formula: KCaCu₅(AsO₄)₄[As(OH)₂O₂]·2H₂O
Mohs hardness: 3
Density: 3.37 g/cm³
Colors: Pale Blue White Colorless
Streak: White
Luster: Vitreous
Transparency: Translucent
Crystal system: Monoclinic
Crystal habit: Bladed Crystals, Radial Aggregates
Cleavage: None
Rarity: Rare
Uses: Collector
Host rock: Hydrothermal Mineral Deposits
Typical price: $50-300 per specimen

Where rockhounds find calcioandyrobertsite

Classic worldwide localities

Tsumeb Mine, Namibia
Torrecillas mine, Chile

Field-hunting tip

Look in hydrothermal mineral deposits country — that is the host setting where calcioandyrobertsite typically forms. If you start seeing duftite, austinite, tsumcorite in float, you are in the right ground. Field specimens usually show a bladed crystals, radial aggregates habit, so train your eye for that shape before scanning the outcrop.

Common questions

How do you identify calcioandyrobertsite?+

Mohs hardness is 3. It typically shows a vitreous luster. The streak is white. Common colors include pale blue, white, colorless.

Where is calcioandyrobertsite found?+

Notable localities include Tsumeb Mine, Namibia; Torrecillas mine, Chile.

How much is calcioandyrobertsite 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 calcioandyrobertsite safe to handle?+

It contains toxic constituents. Contains arsenic, which is toxic. Handle with care, wash hands after touching, and avoid inhalation of dust. Handle with care, avoid grinding or breathing dust, and store separately.

What rocks look like calcioandyrobertsite?+

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

What minerals are found with calcioandyrobertsite?+

Calcioandyrobertsite commonly co-occurs with Duftite, Austinite, Tsumcorite. Spotting any of these in float or country rock is a useful trip signal.

What kind of rock does calcioandyrobertsite form in?+

Calcioandyrobertsite typically forms in hydrothermal mineral deposits. Working float back to the host body is the standard way to chase a fresh occurrence.

What is calcioandyrobertsite used for?+

Calcioandyrobertsite is used in collector.

Find calcioandyrobertsite on the map

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