Comparison · Minerals
Arsenopyrite vs Chalcopyrite
Arsenopyrite and Chalcopyrite are easy to confuse because both are minerals. 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. Below is a side-by-side comparison of their properties and the quick tests that separate them.
Key differences between Arsenopyrite and Chalcopyrite
- 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.
- Streak color differs: Arsenopyrite leaves a dark grayish black streak on unglazed porcelain, Chalcopyrite leaves greenish black.
- Both look metallic, so compare color, tarnish and weight rather than shine.
- Arsenopyrite feels noticeably heavier for its size (specific gravity 6.0–6.2 versus 4.1–4.3 for Chalcopyrite).
- They overlap in yellow and multicolored, but Arsenopyrite also comes in white and gray.
- Well-formed crystals give it away: Arsenopyrite is Monoclinic, Chalcopyrite is Tetragonal.
Arsenopyrite vs Chalcopyrite properties
| Property | Arsenopyrite | Chalcopyrite |
|---|---|---|
| Type | Minerals | Minerals |
| Mohs hardness | 5.5–6 | 3.5–4 |
| Luster | Metallic | Metallic |
| Streak | Dark grayish black | Greenish black |
| Transparency | Opaque | Opaque |
| Specific gravity | 6.0–6.2 | 4.1–4.3 |
| Crystal system | Monoclinic | Tetragonal |
| Common colors | Silver-white, Steel-gray, Tarnished yellowish/iridescent | Brass yellow, Golden yellow, Iridescent tarnish |
| Rarity | common | common |
| Typical specimen value | $2–$150+ | $2–$150+ |
Which is more valuable?
Typical specimens of Arsenopyrite and Chalcopyrite trade in a similar range, around $20.
About Arsenopyrite
Arsenopyrite is an iron arsenic sulfide, FeAsS, and the most common arsenic-bearing mineral in Earth's crust. It crystallizes in the monoclinic system despite forming crystals that often look nearly orthorhombic, and it stands as the primary ore of arsenic. Its silvery, metallic luster and tendency to tarnish to a dull gray or iridescent surface distinguish it at a glance from ordinary pyrite.
About Chalcopyrite
Chalcopyrite is copper iron sulfide, CuFeS2, and the single most important ore mineral of copper worldwide. It crystallizes in the tetragonal system, usually as tarnished brassy-yellow masses or small tetrahedral-looking crystals in hydrothermal veins. Its softness relative to pyrite and its greenish-black streak are the quickest ways to separate it from that more famous fool's-gold mineral.
Arsenopyrite vs Chalcopyrite FAQ
Is Arsenopyrite the same as Chalcopyrite?
No. Both are minerals, but they are distinct species with different hardness, streak or luster. 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.
How can you tell Arsenopyrite from Chalcopyrite?
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. Streak color differs: Arsenopyrite leaves a dark grayish black streak on unglazed porcelain, Chalcopyrite leaves greenish black. Both look metallic, so compare color, tarnish and weight rather than shine.
Which is harder, Arsenopyrite or Chalcopyrite?
Arsenopyrite is harder: Mohs 5.5–6 against Mohs 3.5–4 for Chalcopyrite.
Which is more valuable, Arsenopyrite or Chalcopyrite?
Typical specimens of Arsenopyrite and Chalcopyrite trade in a similar range, around $20.
