Gobelinite is a rare cobalt copper sulfate that forms blocky to thin, lath-like crystals. It occurs in the weathering of cobaltite-gersdorffite and nearby tennantite under acidic conditions. Associated minerals include brochantite, cerussite and gordaite. It was first described from material found in France / Germany.
Is this gobelinite?
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 gobelinite with a known reference. Gobelinite sits at Mohs 2.5, softer than the next harder reference, harder than the previous one.
- 2Check the streakDrag the specimen across an unglazed porcelain plate. Streak: white with a pale green tint.
- 3Read the lusterHold the specimen under a strong light. Luster: vitreous to pearly.
- 4Match the color rangeCompare against the expected color range: pale green, bluish green, grayish green.
- 5Look at form & habitCrystal system: monoclinic. Typical habit: blocky to thin, lath-like crystals.
Often confused with
Gobelinite vs. its common look-alikes, and how to tell them apart in the field.
How to tell apart: Cobaltite is the harder of the two (Mohs 5.5 vs. 2.5); streak differs, so Gobelinite leaves white with a pale green tint, Cobaltite leaves grayish black; luster reads vitreous to pearly on Gobelinite and metallic on Cobaltite.
How to tell apart: Streak differs, so Gobelinite leaves white with a pale green tint, Erythrite leaves pale red to pink; luster reads vitreous to pearly on Gobelinite and subadamantine, pearly on cleavages on Erythrite.
Often found alongside gobelinite
Minerals reported to co-occur with gobelinite. Spotting these in float or country rock is a strong cue you are in the right ground.
All properties
- Chemical formula
- CoCu₄(SO₄)₂(OH)₆·6H₂O
- Mohs hardness
- 2.5
- Density
- 2.95 g/cm³
- Streak
- White with a pale green tint
- Luster
- Vitreous to pearly
- Transparency
- Transparent
- Crystal system
- Monoclinic
- Crystal habit
- Blocky to thin, lath-like crystals
- Cleavage
- None
- Rarity
- Rare
- Uses
- Collector
- Host rock
- hydrothermal cobalt-nickel-arsenide deposits
Where rockhounds find gobelinite
Classic worldwide localities
- Material found in France / Germany
Field-hunting tip
Where it forms: hydrothermal cobalt-nickel-arsenide deposits. If you start seeing skutterudite, malachite, erythrite in float, you are in the right ground. Typical habit: blocky to thin, lath-like crystals. Train your eye for that shape before scanning the outcrop.
Common questions
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Find gobelinite on the map
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