sedimentary
Limestone (Decorative Gravel)
Calcium Carbonate (CaCO3)
Hardness: 3-4 (Mohs scale); Color: light gray to tan; Luster: dull; Crystal Structure: Microcrystalline; Cleavage: None usually visible in aggregate specimens; Specific Gravity: 2.5-2.7
- Hardness
- 3-4 (Mohs scale)
- Color
- light gray to tan
- Luster
- dull
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Physical properties
Hardness: 3-4 (Mohs scale); Color: light gray to tan; Luster: dull; Crystal Structure: Microcrystalline; Cleavage: None usually visible in aggregate specimens; Specific Gravity: 2.5-2.7
Formation & geological history
Formed through the accumulation of shell, coral, algal, and fecal debris in warm, shallow marine waters. This specific specimen appears to be crushed rock aggregate used for landscaping or driveways.
Uses & applications
Primarily used in construction, road base, landscaping, and as a key ingredient in cement.
Geological facts
Limestone makes up about 10% of the total volume of all sedimentary rocks. It is biologically sensitive and can contain microfossils that help geologists date the rock layer.
Field identification & locations
Identify in the field by its light color and a fizzing reaction when exposed to dilute hydrochloric acid. It is commonly found in quarries and as processed aggregate globally.
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