Brochantite is a vibrant, deep-green copper sulfate mineral that typically forms as acicular or prismatic crystal clusters in the oxidized zones of copper deposits. It is often found as a secondary mineral coating other copper minerals, and collectors value it for its intense, vitreous green color.
Is this brochantite?
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 brochantite with a known reference. Brochantite sits at Mohs 3.5-4, softer than the next harder reference, harder than the previous one.
- 2Check the streakDrag the specimen across an unglazed porcelain plate. Streak: pale green.
- 3Read the lusterHold the specimen under a strong light. Luster: vitreous, somewhat pearly on cleavages.
- 4Match the color rangeCompare against the expected color range: emerald-green, dark-green, bright-green, green, black.
- 5Look at form & habitCrystal system: monoclinic. Typical habit: acicular, druse, prismatic.
Often confused with
Brochantite vs. its common look-alikes, and how to tell them apart in the field.
How to tell apart: Luster reads vitreous, somewhat pearly on cleavages on Brochantite and adamantine to vitreous; silky if fibrous; dull to earthy if massive on Malachite.
How to tell apart: Streak differs, so Brochantite leaves pale green, Atacamite leaves apple-green; luster reads vitreous, somewhat pearly on cleavages on Brochantite and adamantine to vitreous on Atacamite.
Often found alongside brochantite
Minerals reported to co-occur with brochantite. Spotting these in float or country rock is a strong cue you are in the right ground.
All properties
- Chemical formula
- Cu₄(SO₄)(OH)₆
- Mohs hardness
- 3.5-4
- Density
- 3.97 g/cm³
- Streak
- Pale green
- Luster
- Vitreous, somewhat pearly on cleavages
- Transparency
- Transparent to translucent
- Crystal system
- Monoclinic
- Crystal habit
- Acicular, druse, prismatic
- Cleavage
- On {100}, perfect
- Rarity
- Common
- Uses
- Collector, Specimen
- Host rock
- Common in the oxidized zone of copper deposits, yet rarely an ore; formed under low acidity, principally in arid regions
Where rockhounds find brochantite
2 mapped spotsClassic worldwide localities
- Bisbee, Cochise Co., and at the Mammoth-St. Anthony mine, Tiger, Pinal Co., Arizona, USA
- Mammoth mine, Tintic, Juab Co., Utah, USA
- Bingham, Socorro Co., New Mexico, USA
- Cerro Gordo mine, Inyo Co., California, USA
- Mednorudyanskoye copper deposit, near Nizhni Tagil, and at Gumeshevsk, southwest of Yekaterinburg (Sverdlovsk), Ural Mountains, Russia
- Băiţa (Rézbánya), Romania
Field-hunting tip
Where it forms: Common in the oxidized zone of copper deposits, yet rarely an ore; formed under low acidity, principally in arid regions. If you start seeing malachite, azurite, tenorite in float, you are in the right ground. Typical habit: acicular, druse, prismatic. Train your eye for that shape before scanning the outcrop. In the U.S., the densest reported localities are in New Mexico, Utah. Start trip planning there.
Common questions
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Find brochantite on the map
RockHoundR shows mapped rockhounding spots, access rules, and lets you log every find.
