Comparison · Minerals
Calcite vs Dumortierite
Calcite and Dumortierite are easy to confuse because both are minerals. Dumortierite is harder (Mohs 7–8.5) than Calcite (Mohs 3), so Dumortierite 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 Dumortierite
- Dumortierite is harder (Mohs 7–8.5) than Calcite (Mohs 3), so Dumortierite will scratch Calcite and not the other way round. A copper coin (Mohs 3.5) scratches it, but a fingernail does not.
- Dumortierite feels noticeably heavier for its size (specific gravity 3.3–3.4 versus 2.7 for Calcite).
- Hold a thin edge to the light: Calcite is transparent, Dumortierite is Translucent to opaque.
- They overlap in blue and pink, but Calcite also comes in clear, yellow, orange, and green and Dumortierite also comes in purple and brown.
- Well-formed crystals give it away: Calcite is trigonal, Dumortierite is Orthorhombic.
Calcite vs Dumortierite properties
| Property | Calcite | Dumortierite |
|---|---|---|
| Type | Minerals | Minerals |
| Mohs hardness | 3 | 7–8.5 |
| Luster | vitreous | Vitreous, silky when fibrous |
| Streak | White | White |
| Transparency | transparent | Translucent to opaque |
| Specific gravity | 2.7 | 3.3–3.4 |
| Crystal system | trigonal | Orthorhombic |
| Common colors | Colorless, White, Yellow, Orange, Blue, Green, Pink | Blue, Violet-blue, Brownish, Pink (rare) |
| Rarity | common | common |
| Typical specimen value | $2–$100+ | $2–$150+ |
Which is more valuable?
Dumortierite is usually the more valuable of the two: a typical collector specimen runs about $20 against $15 for Calcite, and premium Dumortierite 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 Dumortierite
Dumortierite is an aluminum borosilicate mineral crystallizing in the orthorhombic system, best known for its intense blue to violet-blue color caused by trace iron and titanium substitutions. It typically forms fibrous, needle-like crystal aggregates within metamorphic rocks rich in aluminum, such as schists and gneisses subjected to high temperature and pressure. Its deep, saturated blue color has made it a popular but often misidentified substitute for lapis lazuli and sodalite in ornamental carvings.
Calcite vs Dumortierite FAQ
Is Calcite the same as Dumortierite?
No. Both are minerals, but they are distinct species with different hardness, streak or luster. Dumortierite is harder (Mohs 7–8.5) than Calcite (Mohs 3), so Dumortierite 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 Dumortierite?
Dumortierite is harder (Mohs 7–8.5) than Calcite (Mohs 3), so Dumortierite will scratch Calcite and not the other way round. A copper coin (Mohs 3.5) scratches it, but a fingernail does not. Dumortierite feels noticeably heavier for its size (specific gravity 3.3–3.4 versus 2.7 for Calcite). Hold a thin edge to the light: Calcite is transparent, Dumortierite is Translucent to opaque.
Which is harder, Calcite or Dumortierite?
Dumortierite is harder: Mohs 7–8.5 against Mohs 3 for Calcite.
Which is more valuable, Calcite or Dumortierite?
Dumortierite is usually the more valuable of the two: a typical collector specimen runs about $20 against $15 for Calcite, and premium Dumortierite can reach $150 or more.
