Comparison · Metals & Alloys
Aluminum vs Iron
Aluminum and Iron are easy to confuse because both are metals & alloys. Iron is harder (Mohs 4) than Aluminum (Mohs 2.75), so Iron will scratch Aluminum and not the other way round. A copper coin (Mohs 3.5) scratches it, but a fingernail does not. Below is a side-by-side comparison of their properties and the quick tests that separate them.
Key differences between Aluminum and Iron
- Iron is harder (Mohs 4) than Aluminum (Mohs 2.75), so Iron will scratch Aluminum and not the other way round. A copper coin (Mohs 3.5) scratches it, but a fingernail does not.
- Streak color differs: Aluminum leaves a silvery gray streak on unglazed porcelain, Iron leaves gray to dark gray.
- Both look metallic, so compare color, tarnish and weight rather than shine.
- Iron feels noticeably heavier for its size (specific gravity 7.87 versus 2.7 for Aluminum).
- They overlap in gray, but Iron also comes in brown.
Aluminum vs Iron properties
| Property | Aluminum | Iron |
|---|---|---|
| Type | Metals & Alloys | Metals & Alloys |
| Mohs hardness | 2.75 | 4 |
| Luster | metallic | metallic |
| Streak | Silvery gray | Gray to dark gray |
| Transparency | opaque | opaque |
| Specific gravity | 2.7 | 7.87 |
| Crystal system | varies | varies |
| Common colors | Silver, Light gray, Matte gray | Silver-gray, Dark gray, Rust brown |
| Rarity | common | common |
| Typical specimen value | $1–$80+ | $1–$100+ |
Which is more valuable?
Typical specimens of Aluminum and Iron trade in a similar range, around $10.
About Aluminum
Aluminum is a lightweight silvery metal used in cans, foil, tools, frames, cookware, and many everyday objects. It is not usually found as native metal in nature, but it is a common visible material in manufactured scans.
About Iron
Iron is a gray metallic element and the base metal for steel. In everyday scans it may appear as wrought iron, cast iron, raw metal, hardware, tools, or rusty objects.
Aluminum vs Iron FAQ
Is Aluminum the same as Iron?
No. Both are metals & alloys, but they are distinct species with different hardness, streak or luster. Iron is harder (Mohs 4) than Aluminum (Mohs 2.75), so Iron will scratch Aluminum and not the other way round. A copper coin (Mohs 3.5) scratches it, but a fingernail does not.
How can you tell Aluminum from Iron?
Iron is harder (Mohs 4) than Aluminum (Mohs 2.75), so Iron will scratch Aluminum and not the other way round. A copper coin (Mohs 3.5) scratches it, but a fingernail does not. Streak color differs: Aluminum leaves a silvery gray streak on unglazed porcelain, Iron leaves gray to dark gray. Both look metallic, so compare color, tarnish and weight rather than shine.
Which is harder, Aluminum or Iron?
Iron is harder: Mohs 4 against Mohs 2.75 for Aluminum.
Which is more valuable, Aluminum or Iron?
Typical specimens of Aluminum and Iron trade in a similar range, around $10.
