Brochantite
Brochantite is sulfate (copper), Cu₄(SO₄)(OH)₆. In the hand, it rates 3.5 to 4 on the Mohs scale, and it runs emerald green and blackish green. Emerald-green needle sprays and sparkling crusts in copper country, like malachite's glassier, non-fizzing cousin. Arid oxidized copper deposits; notable: Chile, Namibia (Tsumeb), Arizona and Nevada (USA), Morocco.
The geology.
Brochantite carries the formula Cu₄(SO₄)(OH)₆. It belongs to the monoclinic system. The trade files it under sulfate (copper).
It sits at 3.5 to 4 on the Mohs scale. The surface reads vitreous. Light behaviour is transparent to translucent. Specific gravity runs 3.97. The streak is pale green. It breaks with perfect cleavage; brittle.
Emerald-green needle sprays and sparkling crusts in copper country, like malachite's glassier, non-fizzing cousin.
Common cuts are needle sprays, druzy crusts or velvety pockets on matrix.
The origins.
Arid oxidized copper deposits; notable: Chile, Namibia (Tsumeb), Arizona and Nevada (USA), Morocco.
On value, the database notes: collector mineral; rich velvety pockets are mid-range.
Traditional associations.
In energy work traditions, brochantite has little established lore; its green ties it loosely to heart-centered themes.
Included for completeness. Tradition is worth knowing about, and it is worth keeping separate from the mineralogy.
Spotting the real thing.
Emerald-green needle sprays and sparkling crusts in copper country, like malachite's glassier, non-fizzing cousin.
| Looks like | How to tell them apart |
|---|---|
| Malachite | Malachite fizzes in vinegar and forms banded rounded crusts; brochantite doesn't fizz and forms needles |
| Atacamite | Near-identical look, atacamite hails from salty deserts; lab tests separate them definitively |
| Conichalcite | Conichalcite forms apple-green crusts that are harder and duller |
At-home tests.
These checks cost nothing. Daylight, a 10x loupe and a little patience are the whole kit for brochantite.
| Test | What you should see |
|---|---|
| Acid check | No fizz with vinegar (vs malachite) |
| By eye | Needle-spray habit |
| By eye | Pale green streak |
If these checks leave you unsure, that is what appraisers are for. Do not file, heat or soak a piece to find out.
Care & handling.
At 3.5 to 4 on the Mohs scale this is a soft material. Keep it as a display piece, store it apart from harder stones, and skip daily-wear settings.
It breaks with perfect cleavage; brittle, which is worth knowing before you set it or drop it.
Most damage happens during cleaning, not wearing. Avoid steamers, ultrasonic tanks and anything from under the sink.
Copper mineral, wash hands after handling crumbly crusts.
A deeper look.
Extended detail on composition, sourcing, authentication and market value.
The physical record
The formula on record is Cu₄(SO₄)(OH)₆. Crystal system: Monoclinic. Specific gravity: 3.97. Streak: Pale green. Cleavage and fracture: Perfect cleavage; brittle.
How it reaches the market
Arid oxidized copper deposits; notable: Chile, Namibia (Tsumeb), Arizona and Nevada (USA), Morocco.
What it gets confused with
Malachite: Malachite fizzes in vinegar and forms banded rounded crusts; brochantite doesn't fizz and forms needles. Atacamite: Near-identical look, atacamite hails from salty deserts; lab tests separate them definitively. Conichalcite: Conichalcite forms apple-green crusts that are harder and duller.
What it is worth
Collector mineral; rich velvety pockets are mid-range.
One more thing
Brochantite is a main green ingredient of the patina on copper roofs and the Statue of Liberty.
An education-first guide.
There is nothing to buy on this page. Brochantite is not part of our catalogue, and the guide is here anyway because somebody searching the name deserves a straight answer.
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