Smithite is a rare silver arsenic sulfosalt known for its brilliant red color and high refractive index. It typically occurs as small, tabular crystals within the cavities of dolomitic marbles, most famously in the Binnental region of Switzerland. Due to its softness and arsenic content, it is primarily a prize for advanced mineral collectors.
Is this smithite?
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 smithite with a known reference. Smithite sits at Mohs 1.5-2 — softer than the next harder reference, harder than the previous one.
- 2Check the streakDrag the specimen across an unglazed porcelain plate. Smithite leaves a orange-red streak.
- 3Read the lusterHold the specimen under a strong light. Smithite typically shows a adamantine luster.
- 4Match the color rangeCompare against the expected color range: bright red, reddish-orange.
- 5Look at form & habitCrystal system: monoclinic. Typical habit: tabular to blocky crystals, often with striations.
Often confused with
Smithite vs. its common look-alikes — and how to tell them apart in the field.
Often found alongside smithite
Minerals reported to co-occur with smithite. Spotting these in float or country rock is a strong cue you are in the right ground.
All properties
- Chemical formula
- AgAsS₂
- Mohs hardness
- 1.5-2
- Density
- 5.65 g/cm³
- Colors
- Streak
- Orange-red
- Luster
- Adamantine
- Transparency
- Transparent
- Crystal system
- Monoclinic
- Crystal habit
- Tabular to Blocky Crystals, Often with Striations
- Cleavage
- Perfect On {010}
- Rarity
- Rare
- Uses
- Collector
- Host rock
- Dolomitic Marble Cavities
- Typical price
- $100-1500 depending on specimen quality and size
Where rockhounds find smithite
Classic worldwide localities
- Binnental, Switzerland
- Imiter Mine, Morocco
- Jas Roux, France
Field-hunting tip
Look in dolomitic marble cavities country — that is the host setting where smithite typically forms. If you start seeing realgar, galena, sphalerite in float, you are in the right ground. Field specimens usually show a tabular to blocky crystals, often with striations habit, so train your eye for that shape before scanning the outcrop.
Common questions
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Find smithite on the map
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