A copper nugget is a mass of native copper, a metallic element with a distinct copper-red color and high density. It occurs in massive, dendritic, or arborescent form, notably in the basalt flows of Michigan's Keweenaw Peninsula, and can develop a dark brown or green patina through oxidation.
Is this copper nugget?
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 copper nugget with a known reference. Copper Nugget sits at Mohs 2.5-3, softer than the next harder reference, harder than the previous one.
- 2Check the streakDrag the specimen across an unglazed porcelain plate. Copper Nugget leaves a copper-red streak.
- 3Read the lusterHold the specimen under a strong light. Copper Nugget typically shows a metallic luster.
- 4Match the color rangeCompare against the expected color range: reddish-brown, copper-red, tarnished brown, green.
- 5Look at form & habitCrystal system: cubic. Typical habit: massive, dendritic, arborescent, wire, nuggets.
Often confused with
Copper Nugget vs. its common look-alikes, and how to tell them apart in the field.
Often found alongside copper nugget
Minerals reported to co-occur with copper nugget. Spotting these in float or country rock is a strong cue you are in the right ground.
All properties
- Chemical formula
- Cu
- Mohs hardness
- 2.5-3
- Density
- 8.9 g/cm³
- Streak
- Copper-red
- Luster
- Metallic
- Transparency
- Opaque
- Crystal system
- Cubic
- Crystal habit
- Massive, Dendritic, Arborescent, Wire, Nuggets
- Cleavage
- None
- Rarity
- Common
- Uses
- Collector, Ornamental
- Host rock
- Basaltic Lavas, Hydrothermal Veins, Sedimentary Rocks
Where rockhounds find copper nugget
1 mapped spotsClassic worldwide localities
- Keweenaw Peninsula, Michigan, USA
- Corocoro, Bolivia
- Tsumeb, Namibia
- Dzhezkazgan, Kazakhstan
Field-hunting tip
Look in basaltic lavas, hydrothermal veins, sedimentary rocks country, the host setting where copper nugget typically forms. If you start seeing calcite, quartz, prehnite in float, you are in the right ground. Field specimens usually show a massive, dendritic, arborescent, wire, nuggets habit, so train your eye for that shape before scanning the outcrop. In the U.S., the densest reported localities are in California. Start trip planning there.
More copper nugget photos
Common questions
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Find copper nugget on the map
RockHoundR shows mapped rockhounding spots, access rules, and lets you log every find.
