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. Forêtite leaves a very pale blue streak.
- 3Read the lusterHold the specimen under a strong light. Forêtite typically shows a vitreous luster.
- 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 white; luster reads vitreous on Forêtite and pearly on Clinochlore.
How to tell apart: Forêtite is noticeably harder (Mohs 3-4 vs. 2); streak differs, so Forêtite leaves very pale blue, Chamosite leaves white to pale green; 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
- 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
- Metamorphic Rocks
Where rockhounds find forêtite
Classic worldwide localities
- Cap Garonne mine, Provence-Alpes-Côte d'Azur, France
Field-hunting tip
Look in metamorphic rocks country, the host setting where forêtite typically forms. If you start seeing quartz, calcite, hematite in float, you are in the right ground. Field specimens usually show a platy crystals habit, so train your eye for that shape before scanning the outcrop.
Common questions
How do you identify forêtite?+
Where is forêtite found?+
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What rocks look like forêtite?+
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Find forêtite on the map
RockHoundR shows mapped rockhounding spots, access rules, and lets you log every find.
