Comparison · Minerals
Arsenopyrite vs Pyrite
Arsenopyrite and Pyrite are easy to confuse because both are minerals. Both sit near Mohs 5.5–6, so a scratch test alone will not separate them. Lean on luster, streak and heft instead. Below is a side-by-side comparison of their properties and the quick tests that separate them.
Key differences between Arsenopyrite and Pyrite
- Both sit near Mohs 5.5–6, so a scratch test alone will not separate them. Lean on luster, streak and heft instead.
- Streak color differs: Arsenopyrite leaves a dark grayish black streak on unglazed porcelain, Pyrite 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 5 for Pyrite).
- Hold a thin edge to the light: Arsenopyrite is Opaque, Pyrite is opaque.
- They overlap in yellow, but Arsenopyrite also comes in white, gray, and multicolored.
- Well-formed crystals give it away: Arsenopyrite is Monoclinic, Pyrite is cubic.
Arsenopyrite vs Pyrite properties
| Property | Arsenopyrite | Pyrite |
|---|---|---|
| Type | Minerals | Minerals |
| Mohs hardness | 5.5–6 | 6.5 |
| Luster | Metallic | metallic |
| Streak | Dark grayish black | Greenish-black |
| Transparency | Opaque | opaque |
| Specific gravity | 6.0–6.2 | 5 |
| Crystal system | Monoclinic | cubic |
| Common colors | Silver-white, Steel-gray, Tarnished yellowish/iridescent | Brass Yellow, Pale Gold |
| Rarity | common | common |
| Typical specimen value | $2–$150+ | $2–$100+ |
Which is more valuable?
Arsenopyrite is usually the more valuable of the two: a typical collector specimen runs about $20 against $15 for Pyrite, and premium Arsenopyrite can reach $150 or more.
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 Pyrite
Pyrite, commonly known as 'fool's gold,' is an iron sulfide with a metallic luster and pale brass-yellow color. Despite its name, it has significant industrial uses.
Arsenopyrite vs Pyrite FAQ
Is Arsenopyrite the same as Pyrite?
No. Both are minerals, but they are distinct species with different hardness, streak or luster. Both sit near Mohs 5.5–6, so a scratch test alone will not separate them. Lean on luster, streak and heft instead.
How can you tell Arsenopyrite from Pyrite?
Both sit near Mohs 5.5–6, so a scratch test alone will not separate them. Lean on luster, streak and heft instead. Streak color differs: Arsenopyrite leaves a dark grayish black streak on unglazed porcelain, Pyrite leaves greenish-black. Both look metallic, so compare color, tarnish and weight rather than shine.
Which is harder, Arsenopyrite or Pyrite?
Pyrite is harder: Mohs 6.5 against Mohs 5.5–6 for Arsenopyrite.
Which is more valuable, Arsenopyrite or Pyrite?
Arsenopyrite is usually the more valuable of the two: a typical collector specimen runs about $20 against $15 for Pyrite, and premium Arsenopyrite can reach $150 or more.
