Comparison · Minerals
Arsenopyrite vs Bismuth
Arsenopyrite and Bismuth are easy to confuse because both are minerals. Arsenopyrite is harder (Mohs 5.5–6) than Bismuth (Mohs 2–2.5), so Arsenopyrite will scratch Bismuth and not the other way round. A fingernail (Mohs 2.5) scratches it easily. Below is a side-by-side comparison of their properties and the quick tests that separate them.
Key differences between Arsenopyrite and Bismuth
- Arsenopyrite is harder (Mohs 5.5–6) than Bismuth (Mohs 2–2.5), so Arsenopyrite will scratch Bismuth and not the other way round. A fingernail (Mohs 2.5) scratches it easily.
- Streak color differs: Arsenopyrite leaves a dark grayish black streak on unglazed porcelain, Bismuth leaves silvery gray.
- Both look metallic, so compare color, tarnish and weight rather than shine.
- Bismuth feels noticeably heavier for its size (specific gravity 9.7–9.8 versus 6.0–6.2 for Arsenopyrite).
- They overlap in white, gray, yellow, and multicolored, but Bismuth also comes in pink, red, and blue.
- Well-formed crystals give it away: Arsenopyrite is Monoclinic, Bismuth is Trigonal.
Arsenopyrite vs Bismuth properties
| Property | Arsenopyrite | Bismuth |
|---|---|---|
| Type | Minerals | Minerals |
| Mohs hardness | 5.5–6 | 2–2.5 |
| Luster | Metallic | Metallic |
| Streak | Dark grayish black | Silvery gray |
| Transparency | Opaque | Opaque |
| Specific gravity | 6.0–6.2 | 9.7–9.8 |
| Crystal system | Monoclinic | Trigonal |
| Common colors | Silver-white, Steel-gray, Tarnished yellowish/iridescent | Silvery white, Pinkish iridescent tarnish (yellow, red, blue hues) |
| Rarity | common | common |
| Typical specimen value | $2–$150+ | $2–$150+ |
Which is more valuable?
Typical specimens of Arsenopyrite and Bismuth 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 Bismuth
Bismuth is a native element mineral, a brittle, silvery-white metal that develops a strikingly iridescent oxide film in shades of pink, yellow, blue, and green as it tarnishes. It has one of the lowest thermal conductivities of any metal and, unusually for a heavy metal, expands slightly as it solidifies from a melt. Both natural crystals and the far more common laboratory-grown crystals show a distinctive stair-step, hopper-like habit.
Arsenopyrite vs Bismuth FAQ
Is Arsenopyrite the same as Bismuth?
No. Both are minerals, but they are distinct species with different hardness, streak or luster. Arsenopyrite is harder (Mohs 5.5–6) than Bismuth (Mohs 2–2.5), so Arsenopyrite will scratch Bismuth and not the other way round. A fingernail (Mohs 2.5) scratches it easily.
How can you tell Arsenopyrite from Bismuth?
Arsenopyrite is harder (Mohs 5.5–6) than Bismuth (Mohs 2–2.5), so Arsenopyrite will scratch Bismuth and not the other way round. A fingernail (Mohs 2.5) scratches it easily. Streak color differs: Arsenopyrite leaves a dark grayish black streak on unglazed porcelain, Bismuth leaves silvery gray. Both look metallic, so compare color, tarnish and weight rather than shine.
Which is harder, Arsenopyrite or Bismuth?
Arsenopyrite is harder: Mohs 5.5–6 against Mohs 2–2.5 for Bismuth.
Which is more valuable, Arsenopyrite or Bismuth?
Typical specimens of Arsenopyrite and Bismuth trade in a similar range, around $20.
