Comparison · Sedimentary Rocks vs Hydroxide Minerals
Limestone vs Limonite
Limestone and Limonite are easy to confuse. Limonite is harder (Mohs 4.5) than Limestone (Mohs 3), so Limonite will scratch Limestone 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 Limestone and Limonite
- Limonite is harder (Mohs 4.5) than Limestone (Mohs 3), so Limonite will scratch Limestone and not the other way round. A copper coin (Mohs 3.5) scratches it, but a fingernail does not.
- Streak color differs: Limestone leaves a white streak on unglazed porcelain, Limonite leaves yellowish brown.
- Limonite feels noticeably heavier for its size (specific gravity 3.6 versus 2.7 for Limestone).
- They overlap in brown and yellow, but Limestone also comes in white and gray.
Limestone vs Limonite properties
| Property | Limestone | Limonite |
|---|---|---|
| Type | Sedimentary Rocks | Hydroxide Minerals |
| Mohs hardness | 3 | 4.5 |
| Luster | dull | earthy |
| Streak | White | Yellowish brown |
| Transparency | opaque | opaque |
| Specific gravity | 2.7 | 3.6 |
| Crystal system | varies | amorphous |
| Common colors | White, Gray, Tan, Yellow | Yellowish brown, Brown, Dark brown, Ochre yellow |
| Rarity | common | common |
| Typical specimen value | $1–$50+ | $3–$120+ |
Which is more valuable?
Limonite is usually the more valuable of the two: a typical collector specimen runs about $20 against $10 for Limestone, and premium Limonite can reach $120 or more.
About Limestone
Limestone is a sedimentary rock composed mainly of calcium carbonate. It often contains fossils and is the precursor to marble.
About Limonite
Limonite is a field name for poorly crystalline, hydrated iron oxide-hydroxide material, mostly fine-grained goethite. It forms brown earthy masses, botryoidal crusts, and pseudomorphs and has long served as an iron ore and pigment.
Limestone vs Limonite FAQ
Is Limestone the same as Limonite?
No. Limestone is a sedimentary rock while Limonite is a hydroxide mineral. Limonite is harder (Mohs 4.5) than Limestone (Mohs 3), so Limonite will scratch Limestone and not the other way round. A copper coin (Mohs 3.5) scratches it, but a fingernail does not.
How can you tell Limestone from Limonite?
Limonite is harder (Mohs 4.5) than Limestone (Mohs 3), so Limonite will scratch Limestone and not the other way round. A copper coin (Mohs 3.5) scratches it, but a fingernail does not. Streak color differs: Limestone leaves a white streak on unglazed porcelain, Limonite leaves yellowish brown. Limonite feels noticeably heavier for its size (specific gravity 3.6 versus 2.7 for Limestone).
Which is harder, Limestone or Limonite?
Limonite is harder: Mohs 4.5 against Mohs 3 for Limestone.
Which is more valuable, Limestone or Limonite?
Limonite is usually the more valuable of the two: a typical collector specimen runs about $20 against $10 for Limestone, and premium Limonite can reach $120 or more.
