Identification guide · Minerals
How to Identify Chalcopyrite
Chalcopyrite shows a brassy to golden yellow color with a metallic luster, often dulled by an iridescent blue, purple, or green tarnish. Its streak is greenish black to black, distinguishing it immediately from pyrite's greenish-black-to-brownish streak on unglazed porcelain and from gold, which streaks yellow and is far denser and malleable. Hardness of 3.5 to 4 makes it noticeably softer than pyrite, which will scratch it, and chalcopyrite crystals are typically smaller and less well-formed than pyrite's classic cubes.
Chalcopyrite identification checklist
| Color | Brass yellow, Golden yellow, Iridescent tarnish | 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 | 3.5–4 | A steel knife blade (Mohs 5.5) scratches it; a copper coin does not. |
| Streak | Greenish black | Drag a corner across unglazed porcelain (the back of a bathroom tile) and check the powder color. |
| Cleavage | Poor, indistinct | |
| Fracture | Uneven to conchoidal | Broken surfaces show smooth, curved, shell-like scoops. |
| Specific gravity | 4.1–4.3 | Heavier than it looks (specific gravity about 4.199999999999999). |
| Crystal system | Tetragonal |
Chalcopyrite look-alikes and how to tell them apart
Chalcopyrite is harder (Mohs 3.5–4) than Bismuth (Mohs 2–2.5), so Chalcopyrite will scratch Bismuth and not the other way round. A fingernail (Mohs 2.5) scratches it easily. Chalcopyrite vs Bismuth →
Both sit near Mohs 3.5–4, so a scratch test alone will not separate them. Lean on luster, streak and heft instead. Chalcopyrite vs Calcite →
Arsenopyrite is harder (Mohs 5.5–6) than Chalcopyrite (Mohs 3.5–4), so Arsenopyrite will scratch Chalcopyrite and not the other way round. A steel knife blade (Mohs 5.5) scratches it; a copper coin does not. Chalcopyrite vs Arsenopyrite →
Both sit near Mohs 3.5–4, so a scratch test alone will not separate them. Lean on luster, streak and heft instead. Chalcopyrite vs Bornite →
Chalcopyrite identification FAQ
How can you tell if a rock is Chalcopyrite?
Check the color (brass yellow, golden yellow, and iridescent tarnish), the metallic luster, a Mohs hardness of 3.5–4 and a greenish black streak. Photographing it with the StoneSnap app gives a match in seconds.
What is the hardness of Chalcopyrite?
Chalcopyrite has a Mohs hardness of 3.5–4. A steel knife blade (Mohs 5.5) scratches it; a copper coin does not.
What is the difference between Chalcopyrite and Bismuth?
Chalcopyrite (Mohs 3.5–4, metallic luster) and Bismuth (Mohs 2–2.5, metallic luster) look alike, but hardness, streak and heft usually separate them. See the full Chalcopyrite vs Bismuth comparison for a side-by-side table.
Is Chalcopyrite worth anything?
Entry-level Chalcopyrite 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 Chalcopyrite?
Chalcopyrite is most often brass yellow, golden yellow, and iridescent tarnish. Color varies with impurities and locality, so confirm with hardness and luster rather than color alone.
