O'Danielite is a rare secondary mineral found almost exclusively in the oxidized zones of the Tsumeb Mine. It typically forms as delicate, light blue fibrous or crusty aggregates and is highly sought after by mineral collectors specializing in rare arsenic-bearing species.

Hardness

Mohs

Luster

Vitreous

Streak

White

Transparency

Translucent

mineralrare

O'Danielite

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

No image

Is this o'danielite?

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 o'danielite with a known reference. O'Danielite 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. O'Danielite leaves a white streak.
3
Read the luster
Hold the specimen under a strong light. O'Danielite typically shows a vitreous luster.
4
Match the color range
Compare against the expected color range: light blue, bluish white.
5
Look at form & habit
Crystal system: monoclinic. Typical habit: fibrous aggregates, crusts.

Often confused with

O'Danielite 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); streak differs — O'Danielite leaves white, Tsumcorite leaves yellowish.

How to tell apart: O'Danielite is noticeably harder (Mohs 3 vs. 1.5-2).

Compare →

Often found alongside o'danielite

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

All properties

Chemical formula: NaZn₃H₂(AsO₄)₃
Mohs hardness: 3
Density: 3.55 g/cm³
Colors: Light Blue Bluish White
Streak: White
Luster: Vitreous
Transparency: Translucent
Crystal system: Monoclinic
Crystal habit: Fibrous Aggregates, Crusts
Cleavage: None Observed
Rarity: Rare
Uses: Collector
Host rock: Hydrothermal Veins in Dolostone
Typical price: $100-500 for high-quality micro-specimens

Where rockhounds find o'danielite

Classic worldwide localities

Tsumeb Mine, Namibia

Field-hunting tip

Look in hydrothermal veins in dolostone country — that is the host setting where o'danielite typically forms. If you start seeing tsumcorite, arsenic, guerinite in float, you are in the right ground. Field specimens usually show a fibrous aggregates, crusts habit, so train your eye for that shape before scanning the outcrop.

Common questions

How do you identify o'danielite?+

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

Where is o'danielite found?+

Notable localities include Tsumeb Mine, Namibia.

How much is o'danielite worth?+

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

Is o'danielite safe to handle?+

It contains toxic constituents. Contains arsenic; handle with care and wash hands thoroughly after contact. Do not inhale dust or allow to be ingested. Handle with care, avoid grinding or breathing dust, and store separately.

What rocks look like o'danielite?+

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

What minerals are found with o'danielite?+

O'Danielite commonly co-occurs with Tsumcorite, Arsenic, Guerinite. Spotting any of these in float or country rock is a useful trip signal.

What kind of rock does o'danielite form in?+

O'Danielite typically forms in hydrothermal veins in dolostone. Working float back to the host body is the standard way to chase a fresh occurrence.

What is o'danielite used for?+

O'Danielite is used in collector.

Find o'danielite on the map

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