sedimentary
Limestone (Porous/Travertine variant)
Sedimentary Calcium Carbonate (CaCO3)
Hardness: 3-4 (Mohs scale), Color: Cream/Light tan/Off-white, Luster: Dull/Earthy, Structure: Heavily pitted or porous (vuggy), Cleavage: None visible in this form, Specific Gravity: 2.3-2.7
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Physical properties
Hardness: 3-4 (Mohs scale), Color: Cream/Light tan/Off-white, Luster: Dull/Earthy, Structure: Heavily pitted or porous (vuggy), Cleavage: None visible in this form, Specific Gravity: 2.3-2.7
Formation & geological history
Formed through the accumulation of shell, coral, algal, and fecal debris in marine environments, or via chemical precipitation in freshwater/spring settings (travertine). The holes are often caused by the dissolution of organic matter or gas bubbles during formation.
Uses & applications
Primarily used in construction (decorative stone, aggregate), cement production, as a soil conditioner in agriculture, and as a popular choice for rock gardens and aquascaping due to its natural, weathered appearance.
Geological facts
Limestone covers about 10% of the Earth's total land surface. Ancient limestone formations are the primary source of 'Karst' topography, which includes spectacular caves and sinkholes.
Field identification & locations
Identify in the field by its porous texture and reactivity to diluted hydrochloric acid (it will fizz). Commonly found in areas that were once prehistoric seafloors. For collectors, look for versions that may contain fossil imprints.
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