Laffittite is an extremely rare silver mercury arsenic sulfosalt mineral found almost exclusively in the Jas Roux deposit in France. It typically forms small, dark red tabular crystals and is highly sought after by advanced mineral collectors specializing in rare sulfosalts.
Is this laffittite?
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 laffittite with a known reference. Laffittite sits at Mohs 3 — softer than the next harder reference, harder than the previous one.
- 2Check the streakDrag the specimen across an unglazed porcelain plate. Laffittite leaves a light yellow streak.
- 3Read the lusterHold the specimen under a strong light. Laffittite typically shows a adamantine luster.
- 4Match the color rangeCompare against the expected color range: dark red, brownish-red.
- 5Look at form & habitCrystal system: monoclinic. Typical habit: tabular crystals.
Often confused with
Laffittite vs. its common look-alikes — and how to tell them apart in the field.
How to tell apart: Streak differs — Laffittite leaves light yellow, Proustite leaves scarlet.
How to tell apart: Laffittite is noticeably harder (Mohs 3 vs. 1.5-2); streak differs — Laffittite leaves light yellow, Smithite leaves orange-red.
Often found alongside laffittite
Minerals reported to co-occur with laffittite. Spotting these in float or country rock is a strong cue you are in the right ground.
All properties
- Chemical formula
- AgHgAsS₃
- Mohs hardness
- 3
- Density
- 4.8 g/cm³
- Colors
- Streak
- Light Yellow
- Luster
- Adamantine
- Transparency
- Translucent
- Crystal system
- Monoclinic
- Crystal habit
- Tabular Crystals
- Cleavage
- Perfect On {010}
- Rarity
- Rare
- Uses
- Collector
- Host rock
- Hydrothermal Veins
- Typical price
- $200-1000+ for rare specimens
Where rockhounds find laffittite
Classic worldwide localities
- Jas Roux, Hautes-Alpes, France
Field-hunting tip
Look in hydrothermal veins country — that is the host setting where laffittite typically forms. If you start seeing realgar, orpiment, cinnabar in float, you are in the right ground. Field specimens usually show a tabular crystals habit, so train your eye for that shape before scanning the outcrop.
Common questions
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Find laffittite on the map
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