Redgillite is an extremely rare copper sulfate mineral typically found as tiny, vibrant green tabular crystals. It is primarily identified in the oxidation zones of polymetallic hydrothermal deposits, often forming crusts on or alongside other secondary copper minerals.
Is this redgillite?
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 redgillite with a known reference. Redgillite sits at Mohs ~2, softer than the next harder reference, harder than the previous one.
- 2Check the streakDrag the specimen across an unglazed porcelain plate. Streak: white.
- 3Read the lusterHold the specimen under a strong light. Luster: vitreous.
- 4Match the color rangeCompare against the expected color range: grass green.
- 5Look at form & habitCrystal system: monoclinic. Typical habit: bladed.
Often confused with
Redgillite vs. its common look-alikes, and how to tell them apart in the field.
How to tell apart: Brochantite is the harder of the two (Mohs 3.5-4 vs. ~2); streak differs, so Redgillite leaves white, Brochantite leaves pale green.
How to tell apart: Streak differs, so Redgillite leaves white, Posnjakite leaves pale blue.
How to tell apart: Streak differs, so Redgillite leaves white, Langite leaves greenish blue.
Often found alongside redgillite
Minerals reported to co-occur with redgillite. Spotting these in float or country rock is a strong cue you are in the right ground.
All properties
- Chemical formula
- Cu₆SO₄(OH)₁₀(H₂O)
- Mohs hardness
- ~2
- Density
- 3.45 g/cm³
- Colors
- Streak
- White
- Luster
- Vitreous
- Transparency
- Transparent to translucent
- Crystal system
- Monoclinic
- Crystal habit
- Bladed
- Cleavage
- Perfect on {001}, good on {100} and {010}
- Rarity
- Rare
- Uses
- Collector
- Host rock
- A secondary weathering mineral in oxidized copper sulfide veins and post-mining environments
Where rockhounds find redgillite
Classic worldwide localities
- Golden Hugh level of the Silver Gill vein and the No. 2 Level (Old Dutch Level) mine dump at the Red Gill mine, Caldbeck Fells, Cumbria, England
- England at the Penberthy Croft mine, St. Hilary, Cornwall
- Wales at the Frongoch mine, Devil’s Bridge, the Bwlchrhennaid mine, Goginan, the Nant y cagle (Eaglebrook) and Darren mines, Talybont, and the Llechweddhelyg mine, Bontgoch
- Sheefry mine, Co. Mayo, Ireland
Field-hunting tip
Where it forms: A secondary weathering mineral in oxidized copper sulfide veins and post-mining environments. If you start seeing langite, malachite, cuprite in float, you are in the right ground. Typical habit: bladed. Train your eye for that shape before scanning the outcrop.
Common questions
How do you identify redgillite?+
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Is redgillite safe to handle?+
What rocks look like redgillite?+
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Find redgillite on the map
RockHoundR shows mapped rockhounding spots, access rules, and lets you log every find.
