A pearl is a hard, glistening object produced within the soft tissue of a living shelled mollusk or another animal, such as fossil conulariids. Just like the shell of a mollusk, a pearl is composed of calcium carbonate in minute crystalline form, which has deposited in concentric layers. The ideal pearl is perfectly round and smooth, but many other shapes, known as baroque pearls, can occur. The finest quality of natural pearls have been highly valued as gemstones and objects of beauty for many centuries. Because of this, pearl has become a metaphor for something rare, fine, admirable and valuable. The most valuable pearls occur spontaneously in the wild, but are extremely rare. These wild pearls are referred to as natural pearls. Cultured or farmed pearls from pearl oysters and freshwater mussels make up the majority of those currently sold. Imitation pearls are also widely sold in inexpensive jewelry.
| Category | Carbonate mineral, protein |
| Formula, (repeating unit) | Calcium carbonate, CaCO 3, Conchiolin |
| Strunz classification | 05.8 |
| 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 |
| Refractive index | Common pearl: 1.52-1.66, Black pearl: 1.53-1.69 |
| Birefringence | 0.156 |
| Pleochroism | Absent |
| Dispersion | None |
| Ultraviolet fluorescence | White pearls: light blue to light yellow, Yellow and golden pearls: yellow-green, greenish brown to dark brown, Black pearls: commonly pink to orange-red |
Over Pearl
Psychological slasher film about a young woman who is trapped on an isolated farm while tending to her ailing father. She longs for the glamorous life that she sees in Hollywood movies and eventually her temptations and repressions collide. The film was written and directed by Ti West.
Prestaties van Pearl
The movie is a prequel to the film X. It premiered at the 79th Venice International Film Festival.
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Laatste informatie over Pearl bijgewerkt op 10 November 2022.
