fossil
Oyster Shell Fragment
Crassostrea virginica (or related Bivalvia)
Hardness: 3-4 (Mohs); Color: Off-white, cream, with brown or dark purple muscle scar; Luster: Pearly to dull; Composition: Calcium carbonate (Aragonite and Calcite)
- Hardness
- 3-4 (Mohs)
- Color
- Off-white, cream, with brown or dark purple muscle scar
- Luster
- Pearly to dull
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Physical properties
Hardness: 3-4 (Mohs); Color: Off-white, cream, with brown or dark purple muscle scar; Luster: Pearly to dull; Composition: Calcium carbonate (Aragonite and Calcite)
Formation & geological history
Biogenic formation through accretion by marine mollusks; shells consist of organic protein matrices calcified into mineral layers. These fragments are often modern but can be fossilized in sedimentary layers.
Uses & applications
Ecological restoration (oyster reefs), poultry feed (calcium supplement), decorative crafts, and historical archaeology.
Geological facts
Oyster shells are composed of layers of calcium carbonate crystals. The dark spot seen on the fragment is the muscle attachment scar where the adductor muscle was hooked.
Field identification & locations
Identifiable by its irregular, laminated shape and the presence of a smooth, dark muscle scar. Found globally along coastal shorelines and in sedimentary deposits.
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