Sorosite is an extremely rare copper-tin alloy mineral found primarily as tiny grains in alluvial deposits. It is identifiable by its bright metallic luster and silver-white appearance, often requiring analytical testing for positive identification due to its similarity to other tin-bearing minerals.
Is this sorosite?
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 sorosite with a known reference. Sorosite sits at Mohs 5-5.5, softer than the next harder reference, harder than the previous one.
- 2Check the streakDrag the specimen across an unglazed porcelain plate. Streak: silver-white.
- 3Read the lusterHold the specimen under a strong light. Luster: metallic.
- 4Match the color rangeCompare against the expected color range: pinkish tin white.
- 5Look at form & habitCrystal system: hexagonal. Typical habit: disseminated.
Often confused with
Sorosite vs. its common look-alikes, and how to tell them apart in the field.
How to tell apart: Sorosite is noticeably harder (Mohs 5-5.5 vs. 4); streak differs, so Sorosite leaves silver-white, Stannite leaves blackish.
How to tell apart: Sorosite is noticeably harder (Mohs 5-5.5 vs. 2); streak differs, so Sorosite leaves silver-white, Native Tin leaves gray white.
Often found alongside sorosite
Minerals reported to co-occur with sorosite. Spotting these in float or country rock is a strong cue you are in the right ground.
All properties
- Chemical formula
- Cu₁.₁₋₁.₂(Sn,Sb)
- Mohs hardness
- 5-5.5
- Density
- 7.6-7.9 g/cm³
- Colors
- Pinkish tin white
- Streak
- Silver-white
- Luster
- Metallic
- Transparency
- Opaque
- Crystal system
- Hexagonal
- Crystal habit
- Disseminated
- Cleavage
- None
- Rarity
- Rare
- Uses
- Collector
- Host rock
- Very rare, in a gold-PGE placer probably derived from Alaskan-type complexes, formed under low-sulfur reducing conditions (Baimka placer, Russia); in concentrates from precious metal placers (Rio Tamaná, Colombia)
Where rockhounds find sorosite
Classic worldwide localities
- Baimka gold-PGE placer deposit, in the Bol’shoy Anyuy River area, western Chukotka, Russian Far East, Russia (type locality)
- Rio Tamaná, the Department of Chocó, Cauca, Colombia
- Mir zone, Mid-Atlantic Ridge (26◦ N)
Field-hunting tip
Where it forms: Very rare, in a gold-PGE placer probably derived from Alaskan-type complexes, formed under low-sulfur reducing conditions (Baimka placer, Russia); in concentrates from precious metal placers (Rio Tamaná, Colombia). If you start seeing tin, stistaite, herzenbergite in float, you are in the right ground. Typical habit: disseminated. Train your eye for that shape before scanning the outcrop.
Common questions
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Find sorosite on the map
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