Lepidocrocite is a secondary iron oxide mineral typically forming as a result of the oxidation of iron-bearing minerals like pyrite or siderite. It is easily recognized by its distinctive orange-red streak and micaceous or fibrous crystal habits often found within iron-rich gossans.
Is this lepidocrocite?
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 lepidocrocite with a known reference. Lepidocrocite sits at Mohs 5, softer than the next harder reference, harder than the previous one.
- 2Check the streakDrag the specimen across an unglazed porcelain plate. Streak: dull orange.
- 3Read the lusterHold the specimen under a strong light. Luster: submetallic.
- 4Match the color rangeCompare against the expected color range: red, yellowish brown, blackish brown.
- 5Look at form & habitCrystal system: orthorhombic. Typical habit: fibrous, pulverulent, scaly.
Often confused with
Lepidocrocite vs. its common look-alikes, and how to tell them apart in the field.
How to tell apart: Streak differs, so Lepidocrocite leaves dull orange, Goethite leaves brownish yellow, yellow-orange, ocher-yellow; luster reads submetallic on Lepidocrocite and imperfect adamantine metallic to dull earthy; silky when fibrous on Goethite.
How to tell apart: Streak differs, so Lepidocrocite leaves dull orange, Hematite leaves cherry-red or reddish brown; luster reads submetallic on Lepidocrocite and metallic or submetallic to dull on Hematite.
Often found alongside lepidocrocite
Minerals reported to co-occur with lepidocrocite. Spotting these in float or country rock is a strong cue you are in the right ground.
All properties
- Chemical formula
- γ-FeO(OH)
- Mohs hardness
- 5
- Density
- 4.09 g/cm³
- Streak
- Dull orange
- Luster
- Submetallic
- Transparency
- Transparent
- Crystal system
- Orthorhombic
- Crystal habit
- Fibrous, pulverulent, scaly
- Cleavage
- {010}, perfect; {100}, less perfect; {001}, good
- Rarity
- Common
- Uses
- Collector, Scientific research
- Host rock
- A weathering or oxidation product of other iron-bearing minerals, in soils and mineral deposits; a precipitate from ground water
Where rockhounds find lepidocrocite
Classic worldwide localities
- Easton, Northampton Co., Chestnut Hill, Lancaster Co., Pennsylvania, USA
- Iron Mountain mine, Shasta Co., California, USA
- Bisbee, Cochise Co., Arizona, USA
- Eiserfeld, Siegen, and at Herdorf and Müsen, North Rhine-Westphalia, Germany
- Mt. Dünsberg, near Giessen, Hesse, Germany
- Rancié-en-Sem, Ariège, and Chizeuil, Saône-et-Loire, France
Field-hunting tip
Where it forms: A weathering or oxidation product of other iron-bearing minerals, in soils and mineral deposits; a precipitate from ground water. If you start seeing goethite, pyrite in float, you are in the right ground. Typical habit: fibrous, pulverulent, scaly. Train your eye for that shape before scanning the outcrop.
Common questions
How do you identify lepidocrocite?+
Where is lepidocrocite found?+
What rocks look like lepidocrocite?+
What minerals are found with lepidocrocite?+
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What is lepidocrocite used for?+
Find lepidocrocite on the map
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