Comparison · Minerals vs Silicate Minerals
Datolite vs Prehnite
Datolite and Prehnite are easy to confuse. Prehnite is harder (Mohs 6.25) than Datolite (Mohs 5–5.5), so Prehnite will scratch Datolite and not the other way round. A steel knife blade (Mohs 5.5) scratches it; a copper coin does not. Below is a side-by-side comparison of their properties and the quick tests that separate them.
Key differences between Datolite and Prehnite
- Prehnite is harder (Mohs 6.25) than Datolite (Mohs 5–5.5), so Prehnite will scratch Datolite and not the other way round. A steel knife blade (Mohs 5.5) scratches it; a copper coin does not.
- Hold a thin edge to the light: Datolite is Transparent to translucent, Prehnite is translucent.
- They overlap in green and yellow, but Datolite also comes in clear and pink and Prehnite also comes in white and gray.
- Well-formed crystals give it away: Datolite is Monoclinic, Prehnite is orthorhombic.
Datolite vs Prehnite properties
| Property | Datolite | Prehnite |
|---|---|---|
| Type | Minerals | Silicate Minerals |
| Mohs hardness | 5–5.5 | 6.25 |
| Luster | Vitreous, slightly greasy | vitreous |
| Streak | White | White |
| Transparency | Transparent to translucent | translucent |
| Specific gravity | 2.9–3.0 | 2.88 |
| Crystal system | Monoclinic | orthorhombic |
| Common colors | Colorless, White, Pale green, Yellow, Pink | Green, Yellow-green, Yellow, White, Gray |
| Rarity | common | uncommon |
| Typical specimen value | $2–$150+ | $10–$400+ |
Which is more valuable?
Prehnite is usually the more valuable of the two: a typical collector specimen runs about $70 against $20 for Datolite, and premium Prehnite can reach $400 or more.
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.
About Prehnite
Prehnite is a calcium aluminum silicate best known for its soft green to yellow-green color and rounded, botryoidal crystal aggregates. It commonly lines cavities in basalt and is valued by collectors and lapidaries for its translucent glow.
Datolite vs Prehnite FAQ
Is Datolite the same as Prehnite?
No. Datolite is a mineral while Prehnite is a silicate mineral. Prehnite is harder (Mohs 6.25) than Datolite (Mohs 5–5.5), so Prehnite will scratch Datolite and not the other way round. A steel knife blade (Mohs 5.5) scratches it; a copper coin does not.
How can you tell Datolite from Prehnite?
Prehnite is harder (Mohs 6.25) than Datolite (Mohs 5–5.5), so Prehnite will scratch Datolite and not the other way round. A steel knife blade (Mohs 5.5) scratches it; a copper coin does not. Hold a thin edge to the light: Datolite is Transparent to translucent, Prehnite is translucent. They overlap in green and yellow, but Datolite also comes in clear and pink and Prehnite also comes in white and gray.
Which is harder, Datolite or Prehnite?
Prehnite is harder: Mohs 6.25 against Mohs 5–5.5 for Datolite.
Which is more valuable, Datolite or Prehnite?
Prehnite is usually the more valuable of the two: a typical collector specimen runs about $70 against $20 for Datolite, and premium Prehnite can reach $400 or more.
