Identification guide · Minerals
How to Identify Bornite
Bornite shows a metallic luster and a distinctive coppery-bronze color on fresh breaks that rapidly tarnishes to iridescent purple, blue, and pink hues, the trait most collectors use for quick field identification. It has a hardness of about 3, a grayish-black streak, and no visible cleavage, breaking instead with a conchoidal to uneven fracture. Bornite is commonly confused with chalcopyrite and with tarnished chalcocite, but its softer hardness and more colorful iridescence usually distinguish it once a streak test is performed.
Bornite identification checklist
| Color | Copper red to brownish bronze (fresh), Iridescent purple-blue tarnish (peacock ore) | 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 | 3–3.25 | A copper coin (Mohs 3.5) scratches it, but a fingernail does not. |
| Streak | Grayish black | Drag a corner across unglazed porcelain (the back of a bathroom tile) and check the powder color. |
| Cleavage | Poor, indistinct octahedral | |
| Fracture | Conchoidal to uneven | Broken surfaces show smooth, curved, shell-like scoops. |
| Specific gravity | 4.9–5.3 | Very heavy, metallic heft (specific gravity about 5.1). |
| Crystal system | Orthorhombic (pseudocubic) |
Bornite look-alikes and how to tell them apart
Both sit near Mohs 3–3.25, so a scratch test alone will not separate them. Lean on luster, streak and heft instead. Bornite vs Bismuth →
Both sit near Mohs 3–3.25, so a scratch test alone will not separate them. Lean on luster, streak and heft instead. Bornite vs Copper →
Bornite is harder (Mohs 3–3.25) than Covellite (Mohs 1.5–2), so Bornite will scratch Covellite and not the other way round. A fingernail (Mohs 2.5) scratches it easily. Bornite vs Covellite →
Both sit near Mohs 3–3.25, so a scratch test alone will not separate them. Lean on luster, streak and heft instead.
Bornite identification FAQ
How can you tell if a rock is Bornite?
Check the color (copper red to brownish bronze (fresh) and iridescent purple-blue tarnish (peacock ore)), the metallic luster, a Mohs hardness of 3–3.25 and a grayish black streak. Photographing it with the StoneSnap app gives a match in seconds.
What is the hardness of Bornite?
Bornite has a Mohs hardness of 3–3.25. A copper coin (Mohs 3.5) scratches it, but a fingernail does not.
What is the difference between Bornite and Bismuth?
Bornite (Mohs 3–3.25, metallic luster) and Bismuth (Mohs 2–2.5, metallic luster) look alike, but hardness, streak and heft usually separate them. See the full Bornite vs Bismuth comparison for a side-by-side table.
Is Bornite worth anything?
Entry-level Bornite 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 Bornite?
Bornite is most often copper red to brownish bronze (fresh) and iridescent purple-blue tarnish (peacock ore). Color varies with impurities and locality, so confirm with hardness and luster rather than color alone.
