Tooeleite is a rare iron arsenate mineral that typically forms as bright yellow, powdery, or earthy crusts in the oxidation zones of arsenic-rich mines. It is named after its type locality in Tooele County, Utah, where it was originally discovered in association with other secondary arsenic minerals. Collectors prize it as a scientific rarity due to its restricted occurrences and specific geochemical formation requirements.
Is this tooeleite?
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 tooeleite with a known reference. Tooeleite sits at Mohs 2 — softer than the next harder reference, harder than the previous one.
- 2Check the streakDrag the specimen across an unglazed porcelain plate. Tooeleite leaves a yellow streak.
- 3Read the lusterHold the specimen under a strong light. Tooeleite typically shows a earthy luster.
- 4Match the color rangeCompare against the expected color range: yellow, orange-yellow.
- 5Look at form & habitCrystal system: orthorhombic. Typical habit: microcrystalline aggregates, earthy crusts, powdery coatings.
Often confused with
Tooeleite vs. its common look-alikes — and how to tell them apart in the field.
How to tell apart: Scorodite is the harder of the two (Mohs 3.5-4 vs. 2); streak differs — Tooeleite leaves yellow, Scorodite leaves white; luster reads earthy on Tooeleite and vitreous to sub-adamantine on Scorodite.
How to tell apart: Streak differs — Tooeleite leaves yellow, Pharmacosiderite leaves white; luster reads earthy on Tooeleite and adamantine on Pharmacosiderite.
Often found alongside tooeleite
Minerals reported to co-occur with tooeleite. Spotting these in float or country rock is a strong cue you are in the right ground.
All properties
- Chemical formula
- Fe⁶⁺₂(AsO₃)₄(OH)₄·4H₂O
- Mohs hardness
- 2
- Density
- 3.9 g/cm³
- Colors
- Streak
- Yellow
- Luster
- Earthy
- Transparency
- Opaque
- Crystal system
- Orthorhombic
- Crystal habit
- Microcrystalline Aggregates, Earthy Crusts, Powdery Coatings
- Cleavage
- None
- Rarity
- Rare
- Uses
- Collector
- Host rock
- Oxidized Zones of Arsenic-rich Hydrothermal Ore Deposits
- Typical price
- $20-150 for small micro-mounts
Where rockhounds find tooeleite
Classic worldwide localities
- Tooele County, Utah, USA
- San Pedro Mine, New Mexico, USA
- Jachymov, Czech Republic
Field-hunting tip
Look in oxidized zones of arsenic-rich hydrothermal ore deposits country — that is the host setting where tooeleite typically forms. If you start seeing scorodite, arsenopyrite, jarosite in float, you are in the right ground. Field specimens usually show a microcrystalline aggregates, earthy crusts, powdery coatings habit, so train your eye for that shape before scanning the outcrop.
Common questions
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Find tooeleite on the map
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