sedimentary
Crushed Limestone (Gravel)
Calcium Carbonate (CaCO3)
Hardness: 3-4 (Mohs scale); Color: light grey to cream; Luster: dull to earthy; Crystal Structure: Trigonal (as calcite); Cleavage: Rhombohedral (in crystal form); Specific Gravity: 2.7
- Hardness
- 3-4 (Mohs scale)
- Color
- light grey to cream
- Luster
- dull to earthy
Identified More sedimentary →
Identify your own rocks.
Get a report just like this from any photo, free.
Physical properties
Hardness: 3-4 (Mohs scale); Color: light grey to cream; Luster: dull to earthy; Crystal Structure: Trigonal (as calcite); Cleavage: Rhombohedral (in crystal form); Specific Gravity: 2.7
Formation & geological history
Formed by the accumulation of shell, coral, algal, and fecal debris in marine environments. It can also form chemically through the precipitation of calcium carbonate from lake or ocean water.
Uses & applications
Primarily used in construction for road base, concrete aggregate, and railroad ballast. Also used as a soil conditioner in agriculture and as a raw material for lime and cement production.
Geological facts
Limestone makes up about 10% of the total volume of all sedimentary rocks. It is highly susceptible to weathering and is the primary rock type in which karst landscapes (caves and sinkholes) develop.
Field identification & locations
Identify in the field by its light grey color and its vigorous reaction (effervescence) when a small drop of dilute hydrochloric acid or strong vinegar is applied. Commonly found in quarries and as road bedding material.
More like this
Other sedimentary specimens
Sandstone or Siltstone
Arenite (if sandstone)
Sedimentary
Sandstone
Arenite (primarily SiO2)
sedimentary
Shale or Slaty Mudstone
Argillaceous sedimentary rock
sedimentary
Chert Breccia
Brecciated Chert (Microcrystalline Silica)
sedimentary
Sandstone (Quartz-rich)
Arenite (SiO2)
sedimentary
Sandstone (with man-made markings)
Arenite (composed primarily of Quartz, SiO2)
sedimentary