Fossiliferous Limestone

Physical Properties

Hardness: 3 on Mohs scale; Color: Tan, beige, or grey with visible fossil imprints; Luster: Dull or earthy; Crystal structure: Usually microcrystalline matrix with macrofossils; Cleavage: None (rhombohedral cleavage only in pure calcite crystals); Specific gravity: 2.3–2.7

Formation & Geological History

Formed in warm, shallow marine environments through the accumulation of shell, coral, algal, and fecal debris over millions of years. This specimen likely dates from the Phanerozoic Eon, when marine life was abundant.

Uses & Applications

Used primarily in the construction industry as building stone, road base, and in the production of cement. Small specimens are popular for educational purposes and novice fossil collecting.

Geological Facts

Limestone makes up about 10% of the total volume of all sedimentary rocks. It often tells a story of ancient oceans that once covered landmasses that are now high above sea level.

Field Identification & Locations

Identify in the field by looking for visible shells or skeletal fragments; it will also vigorously effervesce (fizz) when a drop of weak hydrochloric acid or vinegar is applied. Commonly found in quarries, road cuts, and riverbeds.

Identified on: 4/13/2026

Mode: Standard