sedimentary
Fossilized Coral
Scleractinia (fossil order), primarily Calcium Carbonate (CaCO3)
Hardness: 3-4 (Mohs scale); Color: White, cream, tan; Luster: Dull to earthy; Crystal structure: Orthorhombic (aragonite) or Trigonal (calcite); Specific Gravity: 2.6-2.7
- Hardness
- 3-4 (Mohs scale)
- Color
- White, cream, tan
- Luster
- Dull to earthy
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Physical properties
Hardness: 3-4 (Mohs scale); Color: White, cream, tan; Luster: Dull to earthy; Crystal structure: Orthorhombic (aragonite) or Trigonal (calcite); Specific Gravity: 2.6-2.7
Formation & geological history
Formed through the fossilization of ancient marine corals. Over millions of years, the organic coral skeleton is replaced by minerals like calcite or chalcedony. Many specimens date from the Devonian to the Pleistocene periods.
Uses & applications
Used primarily for jewelry (cabochons), aquarium decor, home ornamentation, and as collectible geological specimens.
Geological facts
Agatized coral is the state rock of Florida. It can technically be millions of years old and represents a snapshot of ancient seafloors from a time when current landmasses were underwater.
Field identification & locations
Identify by looking for distinct 'flower' or 'honeycomb' patterns (corallites). It is common in coastal areas, limestone quarries, and dry ancient seabed regions like Florida, Indonesia, and Morocco.
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