Arsenocrandallite is a rare phosphate-arsenate mineral belonging to the crandallite group, typically found in the oxidized zones of arsenic-rich ore deposits. It usually forms as small, inconspicuous crusts or fine-grained aggregates that require careful identification through X-ray diffraction or microprobe analysis. Collectors seek it out as a specialized species from specific localities such as the Reaphook Hill occurrence in Australia.

Hardness

Mohs

Luster

Vitreous

Streak

White

Transparency

Translucent

mineralrareCrandallite Group family

Arsenocrandallite

Hardness: 5
Luster: Vitreous
Streak: White
Transparency: Translucent

Is this arsenocrandallite?

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 arsenocrandallite with a known reference. Arsenocrandallite sits at Mohs 5 — softer than the next harder reference, harder than the previous one.
2
Check the streak
Drag the specimen across an unglazed porcelain plate. Arsenocrandallite leaves a white streak.
3
Read the luster
Hold the specimen under a strong light. Arsenocrandallite typically shows a vitreous luster.
4
Match the color range
Compare against the expected color range: white, colorless, pale yellow.
5
Look at form & habit
Crystal system: trigonal. Typical habit: microcrystalline aggregates, crusts, rhombohedral crystals.

Often confused with

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

Often found alongside arsenocrandallite

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

All properties

Chemical formula: CaAl₃(AsO₄)(PO₄)(OH)₆
Mohs hardness: 5
Density: 3.37 g/cm³
Colors: White Colorless Pale Yellow
Streak: White
Luster: Vitreous
Transparency: Translucent
Crystal system: Trigonal
Crystal habit: Microcrystalline Aggregates, Crusts, Rhombohedral Crystals
Cleavage: None
Rarity: Rare
Uses: Collector
Host rock: Oxidized Hydrothermal Arsenic-rich Deposits
Typical price: $50-300 per specimen

Where rockhounds find arsenocrandallite

Classic worldwide localities

Reaphook Hill, South Australia
Gold Hill, Utah, USA
Laurani, Bolivia

Field-hunting tip

Look in oxidized hydrothermal arsenic-rich deposits country — that is the host setting where arsenocrandallite typically forms. If you start seeing arsenic, olivenite, cornubite in float, you are in the right ground. Field specimens usually show a microcrystalline aggregates, crusts, rhombohedral crystals habit, so train your eye for that shape before scanning the outcrop.

Common questions

How do you identify arsenocrandallite?+

Mohs hardness is 5. It typically shows a vitreous luster. The streak is white. Common colors include white, colorless, pale yellow.

Where is arsenocrandallite found?+

Notable localities include Reaphook Hill, South Australia; Gold Hill, Utah, USA; Laurani, Bolivia.

How much is arsenocrandallite 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 arsenocrandallite safe to handle?+

It contains toxic constituents. Contains arsenic, which is toxic. Wash hands thoroughly after handling and avoid inhaling dust. Handle with care, avoid grinding or breathing dust, and store separately.

What rocks look like arsenocrandallite?+

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

What minerals are found with arsenocrandallite?+

Arsenocrandallite commonly co-occurs with Arsenic, Olivenite, Cornubite, Goethite. Spotting any of these in float or country rock is a useful trip signal.

What kind of rock does arsenocrandallite form in?+

Arsenocrandallite typically forms in oxidized hydrothermal arsenic-rich deposits. Working float back to the host body is the standard way to chase a fresh occurrence.

What is arsenocrandallite used for?+

Arsenocrandallite is used in collector.

Find arsenocrandallite on the map

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