Kornelite is a rare iron sulfate mineral that typically forms as a result of the oxidation of pyrite and other iron-bearing sulfides. Collectors look for its distinctive acicular or fibrous habit, often found as delicate clusters or crusts within arid mining environments.
Is this kornelite?
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 kornelite with a known reference. Kornelite sits at Mohs 2.5, softer than the next harder reference, harder than the previous one.
- 2Check the streakDrag the specimen across an unglazed porcelain plate. Streak: pale red.
- 3Read the lusterHold the specimen under a strong light. Luster: silky if fibrous.
- 4Match the color rangeCompare against the expected color range: pale rose pink, violet.
- 5Look at form & habitCrystal system: monoclinic. Typical habit: acicular, encrustations, globular.
Often confused with
Kornelite vs. its common look-alikes, and how to tell them apart in the field.
How to tell apart: Streak differs, so Kornelite leaves pale red, Quenstedtite leaves light violet blue; luster reads silky if fibrous on Kornelite and vitreous on Quenstedtite.
How to tell apart: Streak differs, so Kornelite leaves pale red, Coquimbite leaves white; luster reads silky if fibrous on Kornelite and vitreous on Coquimbite.
How to tell apart: Luster reads silky if fibrous on Kornelite and pearly on {010} on Copiapite.
Often found alongside kornelite
Minerals reported to co-occur with kornelite. Spotting these in float or country rock is a strong cue you are in the right ground.
All properties
- Chemical formula
- Fe₂(SO₄)₃·7H₂O
- Mohs hardness
- 2.5
- Density
- 2.306 g/cm³
- Colors
- Pale rose pinkViolet
- Streak
- Pale red
- Luster
- Silky if fibrous
- Transparency
- Semitransparent
- Crystal system
- Monoclinic
- Crystal habit
- Acicular, encrustations, globular
- Cleavage
- On {100}
- Rarity
- Rare
- Uses
- Collector
- Host rock
- An uncommon secondary mineral formed by oxidation of pyrite
Where rockhounds find kornelite
Classic worldwide localities
- Tintic Standard mine, near Dividend, East Tintic district, Utah Co., USA
- Copper Queen mine, Bisbee, Cochise Co., Arizona, USA
- Island Mountain mine, Trinity Co., and from Coso Hot Springs, Inyo Co., California, USA
- Smolník (Szomolnok), 16 km northeast of Rožňava, Slovakia
- Mt. Kozhokh, Bulgaria
- Lanjarón mineral springs, Granada, Spain
Field-hunting tip
Where it forms: An uncommon secondary mineral formed by oxidation of pyrite. If you start seeing voltaite, coquimbite, römerite in float, you are in the right ground. Typical habit: acicular, encrustations, globular. Train your eye for that shape before scanning the outcrop.
Common questions
How do you identify kornelite?+
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What rocks look like kornelite?+
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Find kornelite on the map
RockHoundR shows mapped rockhounding spots, access rules, and lets you log every find.
