Laforêtite is an extremely rare silver indium sulfide mineral typically found as microscopic grains within other sulfides. It is primarily identified through laboratory analysis of samples from its type locality at the La Fôret mine in France.
Is this laforêtite?
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 laforêtite with a known reference. Laforêtite sits at Mohs 3.5 — softer than the next harder reference, harder than the previous one.
- 2Check the streakDrag the specimen across an unglazed porcelain plate. Laforêtite leaves a black streak.
- 3Read the lusterHold the specimen under a strong light. Laforêtite typically shows a metallic luster.
- 4Match the color rangeCompare against the expected color range: gray, white.
- 5Look at form & habitCrystal system: tetragonal. Typical habit: anhedral grains, inclusions.
Often confused with
Laforêtite vs. its common look-alikes — and how to tell them apart in the field.
How to tell apart: Streak differs — Laforêtite leaves black, Chalcostibite leaves lead-gray.
How to tell apart: Laforêtite is noticeably harder (Mohs 3.5 vs. 2); streak differs — Laforêtite leaves black, Emplectite leaves lead-gray.
Often found alongside laforêtite
Minerals reported to co-occur with laforêtite. Spotting these in float or country rock is a strong cue you are in the right ground.
All properties
- Chemical formula
- AgInS₂
- Mohs hardness
- 3.5
- Density
- 5.68 g/cm³
- Streak
- Black
- Luster
- Metallic
- Transparency
- Opaque
- Crystal system
- Tetragonal
- Crystal habit
- Anhedral Grains, Inclusions
- Cleavage
- None
- Rarity
- Rare
- Uses
- Collector
- Host rock
- Hydrothermal Veins
- Typical price
- $50-300 per specimen
Where rockhounds find laforêtite
Classic worldwide localities
- La Fôret mine, France
- Potosi, Bolivia
Field-hunting tip
Look in hydrothermal veins country — that is the host setting where laforêtite typically forms. If you start seeing sphalerite, galena, chalcopyrite in float, you are in the right ground. Field specimens usually show a anhedral grains, inclusions habit, so train your eye for that shape before scanning the outcrop.
Common questions
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Find laforêtite on the map
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