sedimentary
Black Limestone with Calcite Veins
Limestone (Calcium Carbonate, CaCO3)
Mohs hardness of 3-4; dark gray to black color; dull to sub-vitreous luster; fine-grained texture with white crystalline veins; reacts (fizzes) with dilute hydrochloric acid.
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Physical properties
Mohs hardness of 3-4; dark gray to black color; dull to sub-vitreous luster; fine-grained texture with white crystalline veins; reacts (fizzes) with dilute hydrochloric acid.
Formation & geological history
Formed in marine environments from the accumulation of organic remains and chemical precipitation. The white veins are calcite that filled fractures after the rock was lithified. Found throughout the paleozoic and mesozoic eras.
Uses & applications
Used in construction, as road aggregate, for making cement/lime, and occasionally as decorative pebbles or tumbled stones for landscaping.
Geological facts
Dark color indicates high organic or carbonaceous content. This specific specimen shows classic water-smoothing, likely from a river or beach environment.
Field identification & locations
Identify by its softness (scratchable with a copper penny or steel) and the acid test. Commonly found in coastal or mountainous regions where ancient seabeds have been uplifted.
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