Comparison · Sedimentary Rocks
Caliche vs Diatomite
Caliche and Diatomite are easy to confuse because both are sedimentary rocks. Caliche is harder (Mohs 3) than Diatomite (Mohs 1.5), so Caliche 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 Caliche and Diatomite
- Caliche is harder (Mohs 3) than Diatomite (Mohs 1.5), so Caliche will scratch Diatomite and not the other way round. A fingernail (Mohs 2.5) scratches it easily.
- Streak color differs: Caliche leaves a white to pale tan streak on unglazed porcelain, Diatomite leaves white.
- Caliche feels noticeably heavier for its size (specific gravity 2.4 versus 1 for Diatomite).
Caliche vs Diatomite properties
| Property | Caliche | Diatomite |
|---|---|---|
| Type | Sedimentary Rocks | Sedimentary Rocks |
| Mohs hardness | 3 | 1.5 |
| Luster | dull | dull |
| Streak | White to pale tan | White |
| Transparency | opaque | opaque |
| Specific gravity | 2.4 | 1 |
| Crystal system | varies | varies |
| Common colors | White, Cream, Tan, Gray, Brown | White, Cream, Light gray, Tan |
| Rarity | common | common |
| Typical specimen value | $1–$75+ | $1–$75+ |
Which is more valuable?
Typical specimens of Caliche and Diatomite trade in a similar range, around $10.
About Caliche
Caliche is a hardened calcium carbonate-rich soil or sediment layer, also called calcrete or hardpan, common in arid and semi-arid regions.
About Diatomite
Diatomite is a very light, porous, chalky sedimentary rock made mostly of microscopic diatom remains.
Caliche vs Diatomite FAQ
Is Caliche the same as Diatomite?
No. Both are sedimentary rocks, but they are distinct rock types with different hardness, streak or luster. Caliche is harder (Mohs 3) than Diatomite (Mohs 1.5), so Caliche will scratch Diatomite and not the other way round. A fingernail (Mohs 2.5) scratches it easily.
How can you tell Caliche from Diatomite?
Caliche is harder (Mohs 3) than Diatomite (Mohs 1.5), so Caliche will scratch Diatomite and not the other way round. A fingernail (Mohs 2.5) scratches it easily. Streak color differs: Caliche leaves a white to pale tan streak on unglazed porcelain, Diatomite leaves white. Caliche feels noticeably heavier for its size (specific gravity 2.4 versus 1 for Diatomite).
Which is harder, Caliche or Diatomite?
Caliche is harder: Mohs 3 against Mohs 1.5 for Diatomite.
Which is more valuable, Caliche or Diatomite?
Typical specimens of Caliche and Diatomite trade in a similar range, around $10.
