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.
Is this o'danielite?
5-step field checkRun through these checks against the specimen in your hand. The more boxes tick, the more confident the ID.
- 1Test the hardnessTry 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.
- 2Check the streakDrag the specimen across an unglazed porcelain plate. Streak: white.
- 3Read the lusterHold the specimen under a strong light. Luster: vitreous.
- 4Match the color rangeCompare against the expected color range: violet.
- 5Look at form & habitCrystal 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.
How to tell apart: Tsumcorite is the harder of the two (Mohs 4.5 vs. ~3); streak differs, so O'Danielite leaves white, Tsumcorite leaves yellow.
How to tell apart: Luster reads vitreous on O'Danielite and silky on cleavages on Köttigite.
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
- 4.49 g/cm³
- Colors
- Streak
- White
- Luster
- Vitreous
- Transparency
- Transparent
- Crystal system
- Monoclinic
- Crystal habit
- Fibrous aggregates, crusts
- Cleavage
- {010}, {100}, perfect; {001}, observable
- Rarity
- Rare
- Uses
- Collector
- Host rock
- A rare secondary mineral in the oxidized zone of a dolostone-hosted hydrothermal polymetallic ore deposit
Where rockhounds find o'danielite
Classic worldwide localities
- Tsumeb, Namibia
Field-hunting tip
Where it forms: A rare secondary mineral in the oxidized zone of a dolostone-hosted hydrothermal polymetallic ore deposit. If you start seeing tennantite, chalcocite, cuprian adamite in float, you are in the right ground. Typical habit: fibrous aggregates, crusts. Train your eye for that shape before scanning the outcrop.
Common questions
How do you identify o'danielite?+
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What rocks look like o'danielite?+
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Find o'danielite on the map
RockHoundR shows mapped rockhounding spots, access rules, and lets you log every find.
