Magnussonite is a rare manganese arsenite mineral typically found as vibrant green drusy coatings or small spherical clusters. It is highly prized by micromounters and collectors of rare Swedish manganese minerals, primarily occurring in the metamorphosed iron-manganese deposits of the Långban mining district.
Is this magnussonite?
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 magnussonite with a known reference. Magnussonite sits at Mohs 3.5-4, softer than the next harder reference, harder than the previous one.
- 2Check the streakDrag the specimen across an unglazed porcelain plate. Streak: white.
- 3Read the lusterHold the specimen under a strong light. Luster: vitreous to resinous.
- 4Match the color rangeCompare against the expected color range: blue green, grass green, dark red.
- 5Look at form & habitCrystal system: cubic. Typical habit: drusy aggregates, spherical clusters, minute crystals.
Often confused with
Magnussonite vs. its common look-alikes, and how to tell them apart in the field.
How to tell apart: Luster reads vitreous to resinous on Magnussonite and resinous to subadamantine on Mimetite.
How to tell apart: Streak differs, so Magnussonite leaves white, Dixenite leaves brownish-red; luster reads vitreous to resinous on Magnussonite and metallic to resinous on Dixenite.
Often found alongside magnussonite
Minerals reported to co-occur with magnussonite. Spotting these in float or country rock is a strong cue you are in the right ground.
All properties
- Chemical formula
- Mn²⁺₅(As³⁺O₃)₂(OH)Cl
- Mohs hardness
- 3.5-4
- Density
- 4.14-4.49 g/cm³
- Streak
- White
- Luster
- Vitreous to resinous
- Transparency
- Transparent to translucent
- Crystal system
- Cubic
- Crystal habit
- Drusy aggregates, spherical clusters, minute crystals
- Cleavage
- None
- Rarity
- Rare
- Uses
- Collector
- Host rock
- In a metamorphosed Fe–Mn orebody (Långban, Sweden); very rare in a metamorphosed stratiform zinc orebody (Sterling Hill, New Jersey, USA)
Where rockhounds find magnussonite
Classic worldwide localities
- Sterling Hill, Ogdensburg, Sussex Co., New Jersey, USA
- Långban, Värmland, and in the Brattfors mine, Nordmark, Värmland, Sweden
Field-hunting tip
Where it forms: In a metamorphosed Fe–Mn orebody (Långban, Sweden); very rare in a metamorphosed stratiform zinc orebody (Sterling Hill, New Jersey, USA). If you start seeing dolomite, hausmannite, hematite in float, you are in the right ground. Typical habit: drusy aggregates, spherical clusters, minute crystals. Train your eye for that shape before scanning the outcrop.
Common questions
How do you identify magnussonite?+
Where is magnussonite found?+
Is magnussonite safe to handle?+
What rocks look like magnussonite?+
What minerals are found with magnussonite?+
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What is magnussonite used for?+
Find magnussonite on the map
RockHoundR shows mapped rockhounding spots, access rules, and lets you log every find.
