sedimentary
Fossiliferous Limestone
Biogenic Limestone (Calcium Carbonate, CaCO3)
Hardness: 3-4 (Mohs); Color: Tan, buff, or gray; Luster: Dull to earthy; Structure: Clastic with visible fossil molds and casts (brachiopods/bivalves); Texture: Clastic or bio-crystalline; Specific Gravity: 2.3-2.7
- Hardness
- 3-4 (Mohs)
- Color
- Tan, buff, or gray
- Luster
- Dull to earthy
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Physical properties
Hardness: 3-4 (Mohs); Color: Tan, buff, or gray; Luster: Dull to earthy; Structure: Clastic with visible fossil molds and casts (brachiopods/bivalves); Texture: Clastic or bio-crystalline; Specific Gravity: 2.3-2.7
Formation & geological history
Formed in shallow marine environments through the accumulation of shell fragments and calcium carbonate precipitates. The holes (vugs) are likely created by the leaching of fossils, leaving behind molds. Age varies, often Carboniferous to Devonian for such specimens.
Uses & applications
Primarily used in construction (crushed stone, cement), landscaping (ornamental rocks), and as geological study specimens for paleontologists.
Geological facts
This specific piece is a 'fossil hash,' meaning it contains a densely packed mixture of several types of marine organisms from a prehistoric seafloor.
Field identification & locations
Identify by looking for distinct impressions of shells (brachiopods, mollusks) and a vigorous reaction (fizzing) when exposed to a drop of weak acid (vinegar or HCl). Commonly found in sedimentary basins worldwide.
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