Comparison · Sedimentary Rocks
Diatomite vs Limestone
Diatomite and Limestone are easy to confuse because both are sedimentary rocks. Limestone is harder (Mohs 3) than Diatomite (Mohs 1.5), so Limestone will scratch Diatomite 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 Diatomite and Limestone
- Limestone is harder (Mohs 3) than Diatomite (Mohs 1.5), so Limestone will scratch Diatomite and not the other way round. A fingernail (Mohs 2.5) scratches it easily.
- Limestone feels noticeably heavier for its size (specific gravity 2.7 versus 1 for Diatomite).
- They overlap in white, gray, and brown, but Limestone also comes in yellow.
Diatomite vs Limestone properties
| Property | Diatomite | Limestone |
|---|---|---|
| Type | Sedimentary Rocks | Sedimentary Rocks |
| Mohs hardness | 1.5 | 3 |
| Luster | dull | dull |
| Streak | White | White |
| Transparency | opaque | opaque |
| Specific gravity | 1 | 2.7 |
| Crystal system | varies | varies |
| Common colors | White, Cream, Light gray, Tan | White, Gray, Tan, Yellow |
| Rarity | common | common |
| Typical specimen value | $1–$75+ | $1–$50+ |
Which is more valuable?
Typical specimens of Diatomite and Limestone trade in a similar range, around $10.
About Diatomite
Diatomite is a very light, porous, chalky sedimentary rock made mostly of microscopic diatom remains.
About Limestone
Limestone is a sedimentary rock composed mainly of calcium carbonate. It often contains fossils and is the precursor to marble.
Diatomite vs Limestone FAQ
Is Diatomite the same as Limestone?
No. Both are sedimentary rocks, but they are distinct rock types with different hardness, streak or luster. Limestone is harder (Mohs 3) than Diatomite (Mohs 1.5), so Limestone will scratch Diatomite and not the other way round. A fingernail (Mohs 2.5) scratches it easily.
How can you tell Diatomite from Limestone?
Limestone is harder (Mohs 3) than Diatomite (Mohs 1.5), so Limestone will scratch Diatomite and not the other way round. A fingernail (Mohs 2.5) scratches it easily. Limestone feels noticeably heavier for its size (specific gravity 2.7 versus 1 for Diatomite). They overlap in white, gray, and brown, but Limestone also comes in yellow.
Which is harder, Diatomite or Limestone?
Limestone is harder: Mohs 3 against Mohs 1.5 for Diatomite.
Which is more valuable, Diatomite or Limestone?
Typical specimens of Diatomite and Limestone trade in a similar range, around $10.
