Identification guide · Metals & Alloys
How to Identify Zinc
Zinc is usually bluish silver, gray, and dull silver with a metallic luster and is opaque. It has a Mohs hardness of 2.5. A copper coin (Mohs 3.5) scratches it, but a fingernail does not. Its streak is gray. It is most often confused with Aluminum, Iron, and Lead; the tests below separate them.
Zinc identification checklist
| Color | Bluish silver, Gray, Dull silver | 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 | 2.5 | A copper coin (Mohs 3.5) scratches it, but a fingernail does not. |
| Streak | Gray | Drag a corner across unglazed porcelain (the back of a bathroom tile) and check the powder color. |
| Cleavage | None | |
| Fracture | Ductile to uneven | |
| Specific gravity | 7.14 | Very heavy, metallic heft (specific gravity about 7.14). |
Zinc look-alikes and how to tell them apart
Both sit near Mohs 2.5, so a scratch test alone will not separate them. Lean on luster, streak and heft instead. Zinc vs Aluminum →
Iron is harder (Mohs 4) than Zinc (Mohs 2.5), so Iron will scratch Zinc and not the other way round. A copper coin (Mohs 3.5) scratches it, but a fingernail does not. Zinc vs Iron →
Zinc is harder (Mohs 2.5) than Lead (Mohs 1.5), so Zinc will scratch Lead and not the other way round. A fingernail (Mohs 2.5) scratches it easily. Zinc vs Lead →
Nickel is harder (Mohs 4) than Zinc (Mohs 2.5), so Nickel will scratch Zinc and not the other way round. A copper coin (Mohs 3.5) scratches it, but a fingernail does not.
Field tips
- Look for a bluish-silver to dull gray metal.
- Galvanized zinc coatings can show spangled or mottled crystal patterns.
- Zinc die-cast objects may be gray and moderately heavy.
- Zinc is common in hardware, coatings, batteries, and brass alloys.
Zinc identification FAQ
How can you tell if a rock is Zinc?
Check the color (bluish silver, gray, and dull silver), the metallic luster, a Mohs hardness of 2.5 and a gray streak. Photographing it with the StoneSnap app gives a match in seconds.
What is the hardness of Zinc?
Zinc has a Mohs hardness of 2.5. A copper coin (Mohs 3.5) scratches it, but a fingernail does not.
What is the difference between Zinc and Aluminum?
Zinc (Mohs 2.5, metallic luster) and Aluminum (Mohs 2.75, metallic luster) look alike, but hardness, streak and heft usually separate them. See the full Zinc vs Aluminum comparison for a side-by-side table.
Is Zinc worth anything?
Entry-level Zinc specimens sell for around $1, typical collector pieces about $10, and premium examples $100 or more depending on size, quality and locality.
What color is Zinc?
Zinc is most often bluish silver, gray, and dull silver. Color varies with impurities and locality, so confirm with hardness and luster rather than color alone.
