Proustite is a highly prized silver sulfosalt known for its intense, ruby-red color and adamantine luster. It is light-sensitive and will darken or develop a crust if exposed to strong light over time, so it should be stored in a dark, cool container. Look for it as beautiful, sharp trigonal crystals in low-temperature hydrothermal silver deposits.
Is this proustite?
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 proustite with a known reference. Proustite sits at Mohs 2-2.5 — softer than the next harder reference, harder than the previous one.
- 2Check the streakDrag the specimen across an unglazed porcelain plate. Proustite leaves a scarlet streak.
- 3Read the lusterHold the specimen under a strong light. Proustite typically shows a adamantine luster.
- 4Match the color rangeCompare against the expected color range: scarlet-red, vermilion.
- 5Look at form & habitCrystal system: trigonal. Typical habit: rhombohedral crystals, scalenohedral, massive, disseminated.
Often confused with
Proustite vs. its common look-alikes — and how to tell them apart in the field.
How to tell apart: Streak differs — Proustite leaves scarlet, Pyrargyrite leaves red; luster reads adamantine on Proustite and metallic to adamantine on Pyrargyrite.
How to tell apart: Streak differs — Proustite leaves scarlet, Realgar leaves orange-red; luster reads adamantine on Proustite and resinous on Realgar.
Often found alongside proustite
Minerals reported to co-occur with proustite. Spotting these in float or country rock is a strong cue you are in the right ground.
All properties
- Chemical formula
- Ag₃AsS₃
- Mohs hardness
- 2-2.5
- Density
- 5.57 g/cm³
- Colors
- Streak
- Scarlet
- Luster
- Adamantine
- Transparency
- Translucent
- Crystal system
- Trigonal
- Crystal habit
- Rhombohedral Crystals, Scalenohedral, Massive, Disseminated
- Cleavage
- Distinct On Rhombohedron
- Rarity
- Rare
- Uses
- Collector, Minor Silver Ore
- Host rock
- Hydrothermal Veins
- Typical price
- $50-500 thumbnail, $500-2500 cabinet specimen
Where rockhounds find proustite
Classic worldwide localities
- Chañarcillo, Chile
- Freiberg, Germany
- Jáchymov, Czech Republic
- Guanajuato, Mexico
- Cobalt, Ontario
Field-hunting tip
Look in hydrothermal veins country — that is the host setting where proustite typically forms. If you start seeing pyrargyrite, stephanite, acanthite in float, you are in the right ground. Field specimens usually show a rhombohedral crystals, scalenohedral, massive, disseminated habit, so train your eye for that shape before scanning the outcrop.
Common questions
How do you identify proustite?+
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Find proustite on the map
RockHoundR shows mapped rockhounding spots, access rules, and lets you log every find.
