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 3, softer than the next harder reference, harder than the previous one.
- 2Check the streakDrag the specimen across an unglazed porcelain plate. Streak: cadmium-orange.
- 3Read the lusterHold the specimen under a strong light. Luster: greasy.
- 4Match the color rangeCompare against the expected color range: brown orange, yellow orange.
- 5Look at form & habitCrystal system: monoclinic. Typical habit: bladed, encrustations, powdery.
Often confused with
Tooeleite vs. its common look-alikes, and how to tell them apart in the field.
How to tell apart: Streak differs, so Tooeleite leaves cadmium-orange, Scorodite leaves greenish white; luster reads greasy on Tooeleite and vitreous to subadamantine, subresinous on Scorodite.
How to tell apart: Streak differs, so Tooeleite leaves cadmium-orange, Pharmacosiderite leaves yellowish green; luster reads greasy on Tooeleite and adamantine to greasy 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(AsO₃)₄SO₄(OH)₄·4H₂O
- Mohs hardness
- 3
- Density
- 4.23 g/cm³
- Streak
- Cadmium-orange
- Luster
- Greasy
- Transparency
- Transparent
- Crystal system
- Monoclinic
- Crystal habit
- Bladed, encrustations, powdery
- Cleavage
- On {010}, good
- Rarity
- Rare
- Uses
- Collector
- Host rock
- An uncommon secondary mineral in the oxidized zone of a replacement orebody in metamorphosed limestone
Where rockhounds find tooeleite
Classic worldwide localities
- U.S. mine, Gold Hill, Tooele Co., Utah, USA
Field-hunting tip
Where it forms: An uncommon secondary mineral in the oxidized zone of a replacement orebody in metamorphosed limestone. If you start seeing jarosite, scorodite, sulfur in float, you are in the right ground. Typical habit: bladed, encrustations, powdery. 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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