sedimentary
Fossiliferous Limestone
Carbonate Rock (CaCO3 with organic inclusions)
Hardness: 3-4 (Mohs); Color: Dark gray to black; Luster: Dull/Earthy; Crystal Structure: Microcrystalline with visible bioclasts; Specific Gravity: 2.3-2.7
- Hardness
- 3-4 (Mohs)
- Color
- Dark gray to black
- Luster
- Dull/Earthy
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Physical properties
Hardness: 3-4 (Mohs); Color: Dark gray to black; Luster: Dull/Earthy; Crystal Structure: Microcrystalline with visible bioclasts; Specific Gravity: 2.3-2.7
Formation & geological history
Formed in marine environments through the accumulation of calcium carbonate and organic skeletal remains (crinoids, corals, or brachiopods). Likely Paleozoic to Mesozoic era.
Uses & applications
Aggregates for construction, cement manufacturing, soil conditioner, and decorative stones in landscaping.
Geological facts
Dark grey limestone often gets its color from high organic carbon content. The faint white markings on this specimen are cross-sections of ancient marine fossils weathered smooth by water.
Field identification & locations
Identify in the field by applying a drop of white vinegar; it will effervesce (fizz) as the acid reacts with calcite. Found globally in areas with ancient seafloor history.
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