Kollerite is a rare iron hydroxide. It was approved as a distinct mineral species in 2019. It was first described from the Poudrette Quarry, Mont Saint-Hilaire, La Vallée-du-Richelieu, Montérégie, Québec, Canada.
Is this kollerite?
4-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 kollerite with a known reference. Kollerite sits at Mohs 2-3, softer than the next harder reference, harder than the previous one.
- 2Read the lusterHold the specimen under a strong light. Luster: vitreous.
- 3Match the color rangeCompare against the expected color range: yellow, pale yellow.
- 4Look at form & habitCrystal system: triclinic. Typical habit: acicular crystals, efflorescent crusts.
Often confused with
Kollerite vs. its common look-alikes, and how to tell them apart in the field.
All properties
- Chemical formula
- (NH₄)₂Fe³⁺(SO₃)₂(OH)·H₂O
- Mohs hardness
- 2-3
- Colors
- Luster
- Vitreous
- Transparency
- Translucent
- Crystal system
- Triclinic
- Crystal habit
- Acicular crystals, efflorescent crusts
- Rarity
- Rare
- Uses
- Collector
- Host rock
- oxidized zones of arsenic-rich hydrothermal deposits
Where rockhounds find kollerite
Classic worldwide localities
- Poudrette Quarry, Québec, Canada
Field-hunting tip
Where it forms: oxidized zones of arsenic-rich hydrothermal deposits. If you start seeing mont saint-hilaire, la vallée-du-richelieu, montérégie in float, you are in the right ground. Typical habit: acicular crystals, efflorescent crusts. Train your eye for that shape before scanning the outcrop.
Common questions
How do you identify kollerite?+
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What rocks look like kollerite?+
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Find kollerite on the map
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