Comparison · Minerals
Calcite vs Diaspore
Calcite and Diaspore are easy to confuse because both are minerals. Diaspore is harder (Mohs 6.5–7) than Calcite (Mohs 3), so Diaspore 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 Diaspore
- Diaspore is harder (Mohs 6.5–7) than Calcite (Mohs 3), so Diaspore will scratch Calcite and not the other way round. A copper coin (Mohs 3.5) scratches it, but a fingernail does not.
- Diaspore feels noticeably heavier for its size (specific gravity 3.3–3.5 versus 2.7 for Calcite).
- Hold a thin edge to the light: Calcite is transparent, Diaspore is Transparent to translucent.
- They overlap in clear, yellow, green, and pink, but Calcite also comes in orange and blue and Diaspore also comes in gray, brown, and purple.
- Well-formed crystals give it away: Calcite is trigonal, Diaspore is Orthorhombic.
Calcite vs Diaspore properties
| Property | Calcite | Diaspore |
|---|---|---|
| Type | Minerals | Minerals |
| Mohs hardness | 3 | 6.5–7 |
| Luster | vitreous | Vitreous to pearly on cleavage |
| Streak | White | White |
| Transparency | transparent | Transparent to translucent |
| Specific gravity | 2.7 | 3.3–3.5 |
| Crystal system | trigonal | Orthorhombic |
| Common colors | Colorless, White, Yellow, Orange, Blue, Green, Pink | Colorless, White, Gray, Yellowish, Brown, Green, Violet-pink (color-change) |
| Rarity | common | common |
| Typical specimen value | $2–$100+ | $2–$150+ |
Which is more valuable?
Diaspore is usually the more valuable of the two: a typical collector specimen runs about $20 against $15 for Calcite, and premium Diaspore 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 Diaspore
Diaspore is aluminum oxide hydroxide, AlO(OH), a hard, dense mineral that forms in aluminum-rich metamorphic and hydrothermal environments and ranks among the principal minerals in bauxite ore. It is dimorphous with boehmite, sharing an identical chemical formula but a different crystal structure, and it characteristically splits apart with a sudden crackling sound when heated, a property that inspired its name. Transparent gem-quality crystals, sold as zultanite or csarite, display a striking color change from green to pink or champagne under different lighting.
Calcite vs Diaspore FAQ
Is Calcite the same as Diaspore?
No. Both are minerals, but they are distinct species with different hardness, streak or luster. Diaspore is harder (Mohs 6.5–7) than Calcite (Mohs 3), so Diaspore 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 Diaspore?
Diaspore is harder (Mohs 6.5–7) than Calcite (Mohs 3), so Diaspore will scratch Calcite and not the other way round. A copper coin (Mohs 3.5) scratches it, but a fingernail does not. Diaspore feels noticeably heavier for its size (specific gravity 3.3–3.5 versus 2.7 for Calcite). Hold a thin edge to the light: Calcite is transparent, Diaspore is Transparent to translucent.
Which is harder, Calcite or Diaspore?
Diaspore is harder: Mohs 6.5–7 against Mohs 3 for Calcite.
Which is more valuable, Calcite or Diaspore?
Diaspore is usually the more valuable of the two: a typical collector specimen runs about $20 against $15 for Calcite, and premium Diaspore can reach $150 or more.
