Identification guide · Minerals
How to Identify Copper
Native copper has a distinctive reddish-orange to copper-red color when freshly broken, though most surface specimens are tarnished brown, black, or green from oxidation, and it leaves a shiny copper-red to copper-colored streak. It is soft, at a hardness of 2.5 to 3, highly malleable rather than brittle, and lacks cleavage, instead deforming or showing a hackly fracture when bent or cut. Its malleability, obvious metallic luster, and characteristic streak readily distinguish it from copper-bearing minerals like malachite or azurite, which are brittle, harder, and produce green or blue streaks instead.
Copper identification checklist
| Color | Copper red (fresh), Brown to green-black (tarnished) | Look at a clean, dry surface in daylight. Color zoning, banding or spots are as diagnostic as the hue. |
|---|---|---|
| Luster | Metallic | Turn it under a lamp: a true metallic shine reflects like polished metal and stays opaque at thin edges. |
| Transparency | Opaque | Hold a thin edge up to a bright light and note whether light passes through. |
| Mohs hardness | 2.5–3 | A copper coin (Mohs 3.5) scratches it, but a fingernail does not. |
| Streak | Copper red, shiny | Drag a corner across unglazed porcelain (the back of a bathroom tile) and check the powder color. |
| Cleavage | None | |
| Fracture | Hackly | |
| Specific gravity | 8.9–8.95 | Very heavy, metallic heft (specific gravity about 8.925). |
| Crystal system | Cubic |
Copper look-alikes and how to tell them apart
Both sit near Mohs 2.5–3, so a scratch test alone will not separate them. Lean on luster, streak and heft instead. Copper vs Bornite →
Both sit near Mohs 2.5–3, so a scratch test alone will not separate them. Lean on luster, streak and heft instead. Copper vs Calcite →
Both sit near Mohs 2.5–3, so a scratch test alone will not separate them. Lean on luster, streak and heft instead. Copper vs Astrophyllite →
Copper is harder (Mohs 2.5–3) than Covellite (Mohs 1.5–2), so Copper will scratch Covellite and not the other way round. A fingernail (Mohs 2.5) scratches it easily. Copper vs Covellite →
Copper identification FAQ
How can you tell if a rock is Copper?
Check the color (copper red (fresh) and brown to green-black (tarnished)), the metallic luster, a Mohs hardness of 2.5–3 and a copper red, shiny streak. Photographing it with the StoneSnap app gives a match in seconds.
What is the hardness of Copper?
Copper has a Mohs hardness of 2.5–3. A copper coin (Mohs 3.5) scratches it, but a fingernail does not.
What is the difference between Copper and Bornite?
Copper (Mohs 2.5–3, metallic luster) and Bornite (Mohs 3–3.25, metallic luster) look alike, but hardness, streak and heft usually separate them. See the full Copper vs Bornite comparison for a side-by-side table.
Is Copper worth anything?
Entry-level Copper specimens sell for around $2, typical collector pieces about $20, and premium examples $150 or more depending on size, quality and locality.
What color is Copper?
Copper is most often copper red (fresh) and brown to green-black (tarnished). Color varies with impurities and locality, so confirm with hardness and luster rather than color alone.
