Butlerite is a rare secondary iron sulfate mineral typically found as a dehydration product in the oxidized zones of ore deposits. It most commonly occurs as small, orange-to-yellowish tabular crystals or as efflorescent crusts formed in arid mining environments. Collectors prize it for its vibrant color, though it is fragile and sensitive to humidity.
Is this butlerite?
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 butlerite with a known reference. Butlerite 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. Butlerite leaves a white streak.
- 3Read the lusterHold the specimen under a strong light. Butlerite typically shows a vitreous luster.
- 4Match the color rangeCompare against the expected color range: orange, yellow-orange.
- 5Look at form & habitCrystal system: monoclinic. Typical habit: tabular crystals or earthy to powdery crusts.
Often confused with
Butlerite vs. its common look-alikes — and how to tell them apart in the field.
How to tell apart: Streak differs — Butlerite leaves white, Jarosite leaves yellow.
How to tell apart: Streak differs — Butlerite leaves white, Copiapite leaves yellow; luster reads vitreous on Butlerite and pearly on Copiapite.
How to tell apart: Luster reads vitreous on Butlerite and silky on Fibroferrite.
Often found alongside butlerite
Minerals reported to co-occur with butlerite. Spotting these in float or country rock is a strong cue you are in the right ground.
All properties
- Chemical formula
- Fe³⁺(SO₄)(OH)·2H₂O
- Mohs hardness
- 2.5
- Density
- 2.44 g/cm³
- Colors
- Streak
- White
- Luster
- Vitreous
- Transparency
- Translucent
- Crystal system
- Monoclinic
- Crystal habit
- Tabular Crystals or Earthy to Powdery Crusts
- Cleavage
- Perfect On {010}
- Rarity
- Rare
- Uses
- Collector
- Host rock
- Oxidized Zones of Pyrite-bearing Ore Deposits
- Typical price
- $20-100 for small thumbnail specimens
Where rockhounds find butlerite
Classic worldwide localities
- United Verde mine, Arizona, USA
- Chuquicamata, Chile
- Alcaparrosa mine, Chile
Field-hunting tip
Look in oxidized zones of pyrite-bearing ore deposits country — that is the host setting where butlerite typically forms. If you start seeing copiapite, fibroferrite, halotrichite in float, you are in the right ground. Field specimens usually show a tabular crystals or earthy to powdery crusts habit, so train your eye for that shape before scanning the outcrop.
Common questions
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Find butlerite on the map
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