Aragonite vs Calcite
| Property | Aragonite | Calcite |
|---|---|---|
| Formel | CaCO3 | CaCO3 |
| Kristallsystem | Orthorhombic | Trigonal |
| Mineralklasse | 05 Carbonates and Nitrates | 05 Carbonates and Nitrates |
| Mohshärte | 3.5-4.0 | 3.0 |
| Farbe | Colorless, white, yellow, blue, green | Colorless, white, yellow, orange, blue, green |
| Glanz | Vitreous | Vitreous |
| Strichfarbe | White | White |
| Transparenz | Transparent | Transparent |
| Spaltbarkeit | Poor {010} | Perfect rhombohedral {1011} |
| Bruch | Subconchoidal | Conchoidal |
Key Differences
- ◆ Calcite and aragonite are both CaCO3 polymorphs — same chemistry, different crystal structures.
- ◆ Calcite is trigonal; aragonite is orthorhombic — giving them different crystal habits and cleavage.
- ◆ Aragonite is the high-pressure, metastable polymorph; it converts to calcite over geological time.
- ◆ Aragonite has a higher specific gravity (2.93–2.95) than calcite (2.71).
- ◆ Aragonite forms pearls and nacre (mother of pearl); calcite dominates limestone and marble.