mineral
Seashell (Calcium Carbonate)
Calcium Carbonate (CaCO3)
Hardness: 3-3.5 on Mohs scale. Color: White to cream. Luster: Pearly to dull. Structure: Orthorhombic/Hexagonal (Aragonite/Calcite ratio). Cleavage: None/Fragmentary.
- Hardness
- 3-3
- Color
- White to cream
- Luster
- Pearly to dull
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Physical properties
Hardness: 3-3.5 on Mohs scale. Color: White to cream. Luster: Pearly to dull. Structure: Orthorhombic/Hexagonal (Aragonite/Calcite ratio). Cleavage: None/Fragmentary.
Formation & geological history
Biogenic formation through biological mineralization by marine mollusks; typically Holocene in age for modern beach finds.
Uses & applications
Used for calcium supplements, aquarium substrate, decorative crafts, and as a component in limestone sedimentary rock formation.
Geological facts
While biologically produced, seashells are composed of the minerals calcite and aragonite. Over millions of years, accumulated shells undergo lithification to become limestone.
Field identification & locations
Identify by the fan-like ribbing (costae) and bivalve shape. Common on coastal shorelines globally. High concentrations indicate marine environments.
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