Comparison · Minerals
Calcite vs Datolite
Calcite and Datolite are easy to confuse because both are minerals. Datolite is harder (Mohs 5–5.5) than Calcite (Mohs 3), so Datolite will scratch Calcite 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 Calcite and Datolite
- Datolite is harder (Mohs 5–5.5) than Calcite (Mohs 3), so Datolite will scratch Calcite and not the other way round. A copper coin (Mohs 3.5) scratches it, but a fingernail does not.
- Hold a thin edge to the light: Calcite is transparent, Datolite is Transparent to translucent.
- They overlap in clear, yellow, green, and pink, but Calcite also comes in orange and blue.
- Well-formed crystals give it away: Calcite is trigonal, Datolite is Monoclinic.
Calcite vs Datolite properties
| Property | Calcite | Datolite |
|---|---|---|
| Type | Minerals | Minerals |
| Mohs hardness | 3 | 5–5.5 |
| Luster | vitreous | Vitreous, slightly greasy |
| Streak | White | White |
| Transparency | transparent | Transparent to translucent |
| Specific gravity | 2.7 | 2.9–3.0 |
| Crystal system | trigonal | Monoclinic |
| Common colors | Colorless, White, Yellow, Orange, Blue, Green, Pink | Colorless, White, Pale green, Yellow, Pink |
| Rarity | common | common |
| Typical specimen value | $2–$100+ | $2–$150+ |
Which is more valuable?
Datolite is usually the more valuable of the two: a typical collector specimen runs about $20 against $15 for Calcite, and premium Datolite can reach $150 or more.
About Calcite
Calcite is one of the most common minerals on Earth, found in sedimentary, metamorphic, and igneous rocks. It's the primary component of limestone and marble.
About Datolite
Datolite is a calcium borosilicate mineral crystallizing in the monoclinic system, typically found as glassy, pale green to colorless crystals or as compact, porcelain-like nodules infilling cavities in basalt. It forms primarily through low-temperature hydrothermal activity following the cooling of basaltic lava flows. Its association with native copper deposits in Michigan's Keweenaw Peninsula has made it a favorite among mineral collectors in the region.
Calcite vs Datolite FAQ
Is Calcite the same as Datolite?
No. Both are minerals, but they are distinct species with different hardness, streak or luster. Datolite is harder (Mohs 5–5.5) than Calcite (Mohs 3), so Datolite will scratch Calcite and not the other way round. A copper coin (Mohs 3.5) scratches it, but a fingernail does not.
How can you tell Calcite from Datolite?
Datolite is harder (Mohs 5–5.5) than Calcite (Mohs 3), so Datolite will scratch Calcite and not the other way round. A copper coin (Mohs 3.5) scratches it, but a fingernail does not. Hold a thin edge to the light: Calcite is transparent, Datolite is Transparent to translucent. They overlap in clear, yellow, green, and pink, but Calcite also comes in orange and blue.
Which is harder, Calcite or Datolite?
Datolite is harder: Mohs 5–5.5 against Mohs 3 for Calcite.
Which is more valuable, Calcite or Datolite?
Datolite is usually the more valuable of the two: a typical collector specimen runs about $20 against $15 for Calcite, and premium Datolite can reach $150 or more.
