Laihunite is a rare oxidation product of fayalite that is structurally related to the olivine group. Collectors typically find it as dark, reddish-brown to black masses or grains within metamorphic iron-rich rock formations.
Is this laihunite?
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 laihunite with a known reference. Laihunite sits at Mohs 5.5-6.5, softer than the next harder reference, harder than the previous one.
- 2Check the streakDrag the specimen across an unglazed porcelain plate. Streak: pale brown, blackish brown.
- 3Read the lusterHold the specimen under a strong light. Luster: submetallic to metallic.
- 4Match the color rangeCompare against the expected color range: dark brown, black.
- 5Look at form & habitCrystal system: monoclinic. Typical habit: prismatic crystals, massive.
Often confused with
Laihunite vs. its common look-alikes, and how to tell them apart in the field.
How to tell apart: Streak differs, so Laihunite leaves pale brown, blackish brown, Fayalite leaves white; luster reads submetallic to metallic on Laihunite and vitreous to resinous on fractures on Fayalite.
How to tell apart: Streak differs, so Laihunite leaves pale brown, blackish brown, Hematite leaves cherry-red or reddish brown; luster reads submetallic to metallic on Laihunite and metallic or submetallic to dull on Hematite.
Often found alongside laihunite
Minerals reported to co-occur with laihunite. Spotting these in float or country rock is a strong cue you are in the right ground.
All properties
- Chemical formula
- Fe²⁺Fe³⁺₂(SiO₄)₂
- Mohs hardness
- 5.5-6.5
- Density
- 3.967 g/cm³
- Colors
- Streak
- Pale brown, blackish brown
- Luster
- Submetallic to metallic
- Transparency
- Opaque, translucent in very thin section
- Crystal system
- Monoclinic
- Crystal habit
- Prismatic crystals, massive
- Cleavage
- Good on {001}; perfect on {100}; perfect on {010}
- Rarity
- Rare
- Uses
- Collector
- Host rock
- In a Precambrian metamorphic iron deposit, probably derived by oxidation of fayalite (Little Lai-He Village, China)
Where rockhounds find laihunite
Classic worldwide localities
- St. Peters Dome area, El Paso Co., Colorado, USA
- Little Lai-He village, Liaoning Province, China
- Kamitaga, Shizuoka Prefecture, and Yugawara, Kanagawa Prefecture, Japan
- Cherkassk massif, Kuraminsk, Siberia, Russia
Field-hunting tip
Where it forms: In a Precambrian metamorphic iron deposit, probably derived by oxidation of fayalite (Little Lai-He Village, China). If you start seeing quartz, hypersthene, magnetite in float, you are in the right ground. Typical habit: prismatic crystals, massive. Train your eye for that shape before scanning the outcrop.
Common questions
How do you identify laihunite?+
Where is laihunite found?+
What rocks look like laihunite?+
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Find laihunite on the map
RockHoundR shows mapped rockhounding spots, access rules, and lets you log every find.
