Properties
| Category | Carbonate mineral, protein |
|---|---|
| Formula | Calcium carbonate, CaCO3 Conchiolin |
| Crystal system | Orthorhombic |
| Color | White, pink, silver, cream, brown, green, blue, black, yellow, orange, red, gold, purple, iridescent |
| Cleavage | None |
| Fracture | Uneven, various |
| Mohs scale hardness | 2.5–4.5 |
| Streak | White |
| Specific gravity | 2.60–2.85 |
From the Wikipedia article
A pearl is a hard, shiny object produced within the soft tissue of a living shelled mollusk. Like the shell of a mollusk, a pearl is composed of calcium carbonate in a crystalline form, which is deposited in concentric layers. More commercially valuable pearls are perfectly round and smooth, but many other shapes, known as baroque pearls, can occur. The highest quality of natural pearls have been highly valued as gemstones and objects of beauty for many centuries. In literature, pearls have become a metaphor for something rare, fine, admirable, and valuable.
Source
Source record: crystal-compendium/pearl/minerals.json. Fetched from English Wikipedia by the operator 2 October 2026.
https://en.wikipedia.org/wiki/Pearl — revision id 1377278922. Text and properties from Wikipedia, licensed CC BY-SA 4.0.