Erlianite is a rare phyllosilicate mineral typically found as fibrous or platy blackish aggregates within iron-rich chert formations. It was first identified in China and is highly sought after by systematic mineral collectors due to its restricted locality and complex chemical structure.
Is this erlianite?
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 erlianite with a known reference. Erlianite sits at Mohs 3.7, softer than the next harder reference, harder than the previous one.
- 2Check the streakDrag the specimen across an unglazed porcelain plate. Streak: brownish black.
- 3Read the lusterHold the specimen under a strong light. Luster: silky.
- 4Match the color rangeCompare against the expected color range: black.
- 5Look at form & habitCrystal system: orthorhombic. Typical habit: aggregates, fibrous, platy.
Often confused with
Erlianite vs. its common look-alikes, and how to tell them apart in the field.
How to tell apart: Streak differs, so Erlianite leaves brownish black, Stilpnomelane leaves gray white; luster reads silky on Erlianite and pearly to vitreous on cleavage surface, may be submetallic on Stilpnomelane.
How to tell apart: Erlianite is noticeably harder (Mohs 3.7 vs. 1.5-2); streak differs, so Erlianite leaves brownish black, Minnesotaite leaves white; luster reads silky on Erlianite and greasy to waxy, dull on Minnesotaite.
How to tell apart: Erlianite is noticeably harder (Mohs 3.7 vs. 2.5); streak differs, so Erlianite leaves brownish black, Greenalite leaves greenish gray; luster reads silky on Erlianite and earthy on Greenalite.
Often found alongside erlianite
Minerals reported to co-occur with erlianite. Spotting these in float or country rock is a strong cue you are in the right ground.
All properties
- Chemical formula
- Fe₄Fe₂Si₆O₁₅(OH)₈
- Mohs hardness
- 3.7
- Density
- 3.11 g/cm³
- Colors
- Streak
- Brownish black
- Luster
- Silky
- Transparency
- Opaque
- Crystal system
- Orthorhombic
- Crystal habit
- Aggregates, fibrous, platy
- Cleavage
- Perfect on {001} and {100}
- Rarity
- Rare
- Uses
- Collector
- Host rock
- As coatings along fault surfaces cutting a low-grade metamorphosed volcanic-sedimentary iron formation; presumably formed in a high-pressure, low-temperature environment
Where rockhounds find erlianite
Classic worldwide localities
- Harhada iron mine, along the Jining-Erlian railway, Inner Mongolia, China
Field-hunting tip
Where it forms: As coatings along fault surfaces cutting a low-grade metamorphosed volcanic-sedimentary iron formation; presumably formed in a high-pressure, low-temperature environment. If you start seeing minnesotaite, stilpnomelane, quartz in float, you are in the right ground. Typical habit: aggregates, fibrous, platy. Train your eye for that shape before scanning the outcrop.
Common questions
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Find erlianite on the map
RockHoundR shows mapped rockhounding spots, access rules, and lets you log every find.
