Maghemite is a ferrimagnetic iron oxide that typically forms as an alteration product of magnetite or other iron minerals during weathering or low-temperature oxidation. It is visually indistinguishable from magnetite and hematite without laboratory analysis, but it can be identified by its strong magnetic properties and distinctive reddish-brown streak.
Is this maghemite?
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 maghemite with a known reference. Maghemite 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: brown.
- 3Read the lusterHold the specimen under a strong light. Luster: metallic.
- 4Match the color rangeCompare against the expected color range: dark brown.
- 5Look at form & habitCrystal system: cubic. Typical habit: massive.
Often confused with
Maghemite vs. its common look-alikes, and how to tell them apart in the field.
How to tell apart: Streak differs, so Maghemite leaves brown, Magnetite leaves black.
How to tell apart: Streak differs, so Maghemite leaves brown, Hematite leaves cherry-red or reddish brown.
How to tell apart: Streak differs, so Maghemite leaves brown, Goethite leaves brownish yellow, yellow-orange, ocher-yellow; luster reads metallic on Maghemite and imperfect adamantine metallic to dull earthy; silky when fibrous on Goethite.
Often found alongside maghemite
Minerals reported to co-occur with maghemite. Spotting these in float or country rock is a strong cue you are in the right ground.
All properties
- Chemical formula
- γ-Fe₂O₃
- Mohs hardness
- 5
- Density
- 4.9 g/cm³
- Colors
- Streak
- Brown
- Luster
- Metallic
- Transparency
- Opaque, transparent in thin fragments
- Crystal system
- Cubic
- Crystal habit
- Massive
- Cleavage
- None
- Rarity
- Uncommon
- Uses
- Collector, Scientific research
- Host rock
- Formed by weathering or low-temperature oxidation of spinels containing ferrous iron, commonly magnetite or titanian magnetite
Where rockhounds find maghemite
Classic worldwide localities
- Iron Mountain mine, near Redding, Shasta Co., California, USA
- Bushveld complex, Transvaal, South Africa
- Wabush Iron Formation, Labrador City, Labrador, Newfoundland, Canada
- Steep Rock Lake iron deposits, Ontario, Canada
- Baffinland Iron Mines, northern Baffin Island, Ontario, Canada
- Ontario, Canada
Field-hunting tip
Where it forms: Formed by weathering or low-temperature oxidation of spinels containing ferrous iron, commonly magnetite or titanian magnetite. If you start seeing magnetite, ilmenite, anatase in float, you are in the right ground. Typical habit: massive. Train your eye for that shape before scanning the outcrop.
Common questions
How do you identify maghemite?+
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What rocks look like maghemite?+
What minerals are found with maghemite?+
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Find maghemite on the map
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