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, so Tooeleite leaves yellow, Scorodite leaves white; luster reads earthy on Tooeleite and vitreous to sub-adamantine on Scorodite.
How to tell apart: Streak differs, so 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, 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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