Perroudite is a rare mercury silver halide mineral typically found as tiny, vibrant red, acicular needles in oxidized ore deposits. It is highly prized by collectors for its brilliant color and crystal habit, though it is almost exclusively found as microscopic specimens.
Is this perroudite?
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 perroudite with a known reference. Perroudite sits at Mohs 2, softer than the next harder reference, harder than the previous one.
- 2Check the streakDrag the specimen across an unglazed porcelain plate. Streak: reddish orange.
- 3Read the lusterHold the specimen under a strong light. Luster: vitreous to adamantine.
- 4Match the color rangeCompare against the expected color range: light red.
- 5Look at form & habitCrystal system: orthorhombic. Typical habit: acicular, aggregates, prismatic.
Often confused with
Perroudite vs. its common look-alikes, and how to tell them apart in the field.
How to tell apart: Streak differs, so Perroudite leaves reddish orange, Cinnabar leaves scarlet; luster reads vitreous to adamantine on Perroudite and adamantine, inclining to metallic when dark; dull in friable material on Cinnabar.
How to tell apart: Streak differs, so Perroudite leaves reddish orange, Iodargyrite leaves yellow, shining; luster reads vitreous to adamantine on Perroudite and resinous to adamantine, pearly on cleavage surfaces on Iodargyrite.
Often found alongside perroudite
Minerals reported to co-occur with perroudite. Spotting these in float or country rock is a strong cue you are in the right ground.
All properties
- Chemical formula
- Hg₅Ag₄S₅(I,Br,Cl)₂
- Mohs hardness
- 2
- Density
- 6.928 g/cm³
- Colors
- Streak
- Reddish orange
- Luster
- Vitreous to adamantine
- Transparency
- Transparent
- Crystal system
- Orthorhombic
- Crystal habit
- Acicular, aggregates, prismatic
- Cleavage
- Perfect on {100}
- Rarity
- Rare
- Uses
- Collector
- Host rock
- An alteration of tennantite in sandstones and conglomerates (Cap Garonne mine, France); in a quartz vein carrying oxidized galena (Coppin Pool, Australia)
Where rockhounds find perroudite
Classic worldwide localities
- Cap Garonne mine, near le Pradet, Var, France (type locality)
- Schöne Aussicht mine, near Dernbach, North Rhine-Westphalia, Germany
- Broken Hill, New South Wales, Australia
- Coppin Pool, Pilbara district, and from the Anticline prospect, 11 km west-southwest of Ashburton Downs homestead, Capricorn Range, Western Australia
- Tsumeb, Namibia
Field-hunting tip
Where it forms: An alteration of tennantite in sandstones and conglomerates (Cap Garonne mine, France); in a quartz vein carrying oxidized galena (Coppin Pool, Australia). If you start seeing secondary copper minerals, iodargyrite, gold in float, you are in the right ground. Typical habit: acicular, aggregates, prismatic. Train your eye for that shape before scanning the outcrop.
Common questions
How do you identify perroudite?+
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Is perroudite safe to handle?+
What rocks look like perroudite?+
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Find perroudite on the map
RockHoundR shows mapped rockhounding spots, access rules, and lets you log every find.
