Forêtite is a rare copper aluminum arsenate, typically pale sky blue to aqua. It was approved as a distinct mineral species in 2011. It was first described from the Cap Garonne mine, Var, Provence-Alpes-Côte d'Azur, France.
Is this forêtite?
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 forêtite with a known reference. Forêtite sits at Mohs 3-4, softer than the next harder reference, harder than the previous one.
- 2Check the streakDrag the specimen across an unglazed porcelain plate. Streak: very pale blue.
- 3Read the lusterHold the specimen under a strong light. Luster: vitreous.
- 4Match the color rangeCompare against the expected color range: pale sky blue, aqua.
- 5Look at form & habitCrystal system: triclinic. Typical habit: platy crystals.
Often confused with
Forêtite vs. its common look-alikes, and how to tell them apart in the field.
How to tell apart: Streak differs, so Forêtite leaves very pale blue, Clinochlore leaves greenish white to white; luster reads vitreous on Forêtite and pearly, greasy, dull on Clinochlore.
How to tell apart: Streak differs, so Forêtite leaves very pale blue, Chamosite leaves green to gray; luster reads vitreous on Forêtite and pearly on Chamosite.
Often found alongside forêtite
Minerals reported to co-occur with forêtite. Spotting these in float or country rock is a strong cue you are in the right ground.
All properties
- Chemical formula
- Cu₂Al₂(AsO₄)(OH,O,H₂O)₆
- Mohs hardness
- 3-4
- Density
- 3.286 g/cm³
- Colors
- Pale sky blueAqua
- Streak
- Very pale blue
- Luster
- Vitreous
- Transparency
- Transparent
- Crystal system
- Triclinic
- Crystal habit
- Platy crystals
- Cleavage
- Poor on (010)
- Rarity
- Rare
- Uses
- Collector
- Host rock
- A secondary mineral in the oxidation zone of a hydrothermal sulfide deposit presumably formed under acidic conditions
Where rockhounds find forêtite
Classic worldwide localities
- Annex S chamber and pillar 44b, Cap Garonne mine, Var, Provence-Alpes-Côte d’Azur and at the Salsigne gold mine, Aude, Languedoc-Roussillon, France
Field-hunting tip
Where it forms: A secondary mineral in the oxidation zone of a hydrothermal sulfide deposit presumably formed under acidic conditions. If you start seeing bariopharmacoalumite, cyanotrichite, parnauite in float, you are in the right ground. Typical habit: platy crystals. Train your eye for that shape before scanning the outcrop.
Common questions
How do you identify forêtite?+
Where is forêtite found?+
Is forêtite safe to handle?+
What rocks look like forêtite?+
What minerals are found with forêtite?+
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What is forêtite used for?+
Find forêtite on the map
RockHoundR shows mapped rockhounding spots, access rules, and lets you log every find.
