sedimentary
Gravel / Limestone Fragment
Calcium Carbonate (CaCO3) / Fine-grained Sedimentary Rock
Hardness: 3-4 on Mohs scale. Color: Dull gray to charcoal with light flecks. Luster: Earthy to sub-vitreous. Fracture: Irregular to sub-conchoidal.
- Hardness
- 3-4 on Mohs scale
- Color
- Dull gray to charcoal with light flecks
- Luster
- Earthy to sub-vitreous
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Physical properties
Hardness: 3-4 on Mohs scale. Color: Dull gray to charcoal with light flecks. Luster: Earthy to sub-vitreous. Fracture: Irregular to sub-conchoidal.
Formation & geological history
Formed from the accumulation and compaction of organic debris, marine organism shells, or mineral precipitation in shallow aquatic environments over millions of years.
Uses & applications
Commonly crushed for construction aggregate, road base material, concrete production, and landscape graveling.
Geological facts
Limestone and related gravel rocks cover about 10% of the Earth's total sedimentary rock volume and often contain tiny microfossils.
Field identification & locations
Can be identified in the field by reacting (effervescing) with dilute hydrochloric acid or vinegar. Found abundantly in riverbeds, quarries, and gravel driveways.
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