sedimentary
Likely limestone or chalky carbonate rock
Calcite-rich carbonate rock; chiefly calcium carbonate (CaCO₃)
AI-generated identification · may be incorrectWhite to pale gray, dull earthy luster, fine-grained and porous with an irregular fracture. Calcite has Mohs hardness 3 and commonly effervesces vigorously with dilute hydrochloric acid; exact texture is unclear from the image.
Identified More sedimentary →
Explore Likely limestone or chalky carbonate rock in the encyclopedia →Identify your own rocks.
Get a report just like this from any photo, free.
Physical properties
White to pale gray, dull earthy luster, fine-grained and porous with an irregular fracture. Calcite has Mohs hardness 3 and commonly effervesces vigorously with dilute hydrochloric acid; exact texture is unclear from the image.
Formation & geological history
Formed from accumulated marine carbonate mud, shells, or skeletal debris, commonly in shallow seas; age cannot be determined visually and may range from Paleozoic to recent deposits.
Uses & applications
Used for cement, lime, aggregate, soil amendment, and building stone; non-gem quality pieces have little jewelry value.
Geological facts
Calcite-rich rocks are widespread and may include chalk, micritic limestone, marl, or weathered carbonate material. Their pale color and softness distinguish them from most silicate rocks.
Field identification & locations
Look for visible fossil fragments, powdery texture, and acid reaction; a steel nail usually does not scratch fresh limestone easily, but calcite can be scratched. Common worldwide, especially in former marine basins.
More like this
Other sedimentary specimens
Fossiliferous Sedimentary Rock
Sedimentary limestone with invertebrate fossil imprint
fossil
Sandstone or Siltstone
Arenite (if sandstone)
Sedimentary
Sandstone
Arenite
sedimentary
Quartz pebble
Silicon dioxide (SiO2)
sedimentary
Sedimentary Sandstone
Arenite (Sedimentary Rock)
sedimentary
Generic Pebble / Rock Fragment
Lithic fragment / Weathered rock
sedimentary