sedimentary

Fossiliferous Limestone (Coral Rag)

Biogenic Limestone (Calcium Carbonate, CaCO3)

AI-generated identification · may be incorrect

Hardness: 3-4 (Mohs), Color: White to light tan, Luster: Dull/Earthy, Crystal Structure: Orthorhombic (Aragonite) or Trigonal (Calcite), Cleavage: None visible, Specific Gravity: 2.3-2.7

Identified June 7, 2026More sedimentary →

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Physical properties

Hardness: 3-4 (Mohs), Color: White to light tan, Luster: Dull/Earthy, Crystal Structure: Orthorhombic (Aragonite) or Trigonal (Calcite), Cleavage: None visible, Specific Gravity: 2.3-2.7

Formation & geological history

Formed from the accumulation of skeletal fragments of marine organisms such as coral, mollusks, and foraminifera in shallow, warm sea environments. This specimen appears to be of Holocene or Pleistocene origin.

Uses & applications

Used as a building material in tropical coastal regions, in the manufacturing of cement, as a decorative garden stone, and as substrate for marine aquariums.

Geological facts

Limestone is responsible for most of the world's cave systems. When composed primarily of coral fragments, it is often referred to as 'Coral Rag' and is commonly found in ancient uplifted reef systems.

Field identification & locations

Identify by its porous, skeletal texture and characteristic fizzing reaction (effervescence) when exposed to dilute hydrochloric acid. It is commonly found along coastlines and in ancient seabed deposits.