Comparison · Minerals
Calcite vs Dioptase
Calcite and Dioptase are easy to confuse because both are minerals. Dioptase is harder (Mohs 5) than Calcite (Mohs 3), so Dioptase 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 Dioptase
- Dioptase is harder (Mohs 5) than Calcite (Mohs 3), so Dioptase will scratch Calcite and not the other way round. A copper coin (Mohs 3.5) scratches it, but a fingernail does not.
- Streak color differs: Calcite leaves a white streak on unglazed porcelain, Dioptase leaves green.
- Dioptase feels noticeably heavier for its size (specific gravity 3.28–3.35 versus 2.7 for Calcite).
- Hold a thin edge to the light: Calcite is transparent, Dioptase is Transparent to translucent.
- They overlap in green, but Calcite also comes in clear, yellow, orange, blue, and pink.
- Well-formed crystals give it away: Calcite is trigonal, Dioptase is Trigonal.
Calcite vs Dioptase properties
| Property | Calcite | Dioptase |
|---|---|---|
| Type | Minerals | Minerals |
| Mohs hardness | 3 | 5 |
| Luster | vitreous | Vitreous |
| Streak | White | Green |
| Transparency | transparent | Transparent to translucent |
| Specific gravity | 2.7 | 3.28–3.35 |
| Crystal system | trigonal | Trigonal |
| Common colors | Colorless, White, Yellow, Orange, Blue, Green, Pink | Emerald green, Bluish green |
| Rarity | common | common |
| Typical specimen value | $2–$100+ | $2–$150+ |
Which is more valuable?
Dioptase is usually the more valuable of the two: a typical collector specimen runs about $20 against $15 for Calcite, and premium Dioptase 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 Dioptase
Dioptase is a copper cyclosilicate mineral, Cu6Si6O18·6H2O, prized for an intense emerald-green color that rivals fine emerald despite being a completely different mineral species. It forms in the oxidized zones of copper ore deposits under arid conditions, typically as small but brilliantly lustrous crystals. Dioptase is too soft and brittle to be widely used as a gemstone, so its value lies almost entirely with mineral collectors.
Calcite vs Dioptase FAQ
Is Calcite the same as Dioptase?
No. Both are minerals, but they are distinct species with different hardness, streak or luster. Dioptase is harder (Mohs 5) than Calcite (Mohs 3), so Dioptase 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 Dioptase?
Dioptase is harder (Mohs 5) than Calcite (Mohs 3), so Dioptase will scratch Calcite and not the other way round. A copper coin (Mohs 3.5) scratches it, but a fingernail does not. Streak color differs: Calcite leaves a white streak on unglazed porcelain, Dioptase leaves green. Dioptase feels noticeably heavier for its size (specific gravity 3.28–3.35 versus 2.7 for Calcite).
Which is harder, Calcite or Dioptase?
Dioptase is harder: Mohs 5 against Mohs 3 for Calcite.
Which is more valuable, Calcite or Dioptase?
Dioptase is usually the more valuable of the two: a typical collector specimen runs about $20 against $15 for Calcite, and premium Dioptase can reach $150 or more.
