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, so Proustite leaves scarlet, Pyrargyrite leaves red; luster reads adamantine on Proustite and metallic to adamantine on Pyrargyrite.
How to tell apart: Streak differs, so 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, 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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How much is proustite worth?+
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What minerals are found with proustite?+
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Find proustite on the map
RockHoundR shows mapped rockhounding spots, access rules, and lets you log every find.
