Synadelphite is a rare manganese arsenate mineral typically found as reddish-brown prismatic crystals or radial clusters. It is highly valued by mineral collectors for its complexity and association with the unique manganese deposits of Långban, Sweden.
Is this synadelphite?
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 synadelphite with a known reference. Synadelphite sits at Mohs 4.5 — softer than the next harder reference, harder than the previous one.
- 2Check the streakDrag the specimen across an unglazed porcelain plate. Synadelphite leaves a yellowish-brown streak.
- 3Read the lusterHold the specimen under a strong light. Synadelphite typically shows a vitreous to greasy luster.
- 4Match the color rangeCompare against the expected color range: brown, reddish-brown, yellowish-brown.
- 5Look at form & habitCrystal system: orthorhombic. Typical habit: prismatic crystals, radial aggregates, crusts.
Often confused with
Synadelphite vs. its common look-alikes — and how to tell them apart in the field.
How to tell apart: Streak differs — Synadelphite leaves yellowish-brown, Allactite leaves light brown; luster reads vitreous to greasy on Synadelphite and vitreous on Allactite.
How to tell apart: Streak differs — Synadelphite leaves yellowish-brown, Brandtite leaves white; luster reads vitreous to greasy on Synadelphite and vitreous on Brandtite.
How to tell apart: Streak differs — Synadelphite leaves yellowish-brown, Adelite leaves white; luster reads vitreous to greasy on Synadelphite and vitreous on Adelite.
Often found alongside synadelphite
Minerals reported to co-occur with synadelphite. Spotting these in float or country rock is a strong cue you are in the right ground.
All properties
- Chemical formula
- Mn²⁺₉(As³⁺O₃)(As⁵⁺O₄)₂(OH)₉
- Mohs hardness
- 4.5
- Density
- 3.5 g/cm³
- Streak
- Yellowish-brown
- Luster
- Vitreous to Greasy
- Transparency
- Translucent
- Crystal system
- Orthorhombic
- Crystal habit
- Prismatic Crystals, Radial Aggregates, Crusts
- Cleavage
- Perfect On {001}
- Rarity
- Rare
- Uses
- Collector
- Host rock
- Metamorphosed Manganese Ore Deposits
- Typical price
- $50-300 for small thumbnail specimens
Where rockhounds find synadelphite
Classic worldwide localities
- Nordmark, Värmland, Sweden
- Långban, Värmland, Sweden
Field-hunting tip
Look in metamorphosed manganese ore deposits country — that is the host setting where synadelphite typically forms. If you start seeing hausmannite, barite, svabite in float, you are in the right ground. Field specimens usually show a prismatic crystals, radial aggregates, crusts habit, so train your eye for that shape before scanning the outcrop.
Common questions
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Find synadelphite on the map
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