sedimentary

Fossiliferous Limestone

Biogenic Sedimentary Rock (CaCO3)

Hardness of 3 on the Mohs scale, grayish to tan color, dull to earthy luster, and reacts strongly with hydrochloric acid.

Identified November 7, 2026More sedimentary →

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Physical properties

Hardness of 3 on the Mohs scale, grayish to tan color, dull to earthy luster, and reacts strongly with hydrochloric acid.

Formed through the accumulation and compaction of ancient marine shell fragments and skeletal remains over millions of years.

Used in construction, production of lime and cement, and as a decorative building stone.

Fossiliferous limestone provides a direct record of past marine environments and ancient biodiversity.

Identify in the field by visible fossil fragments embedded in the rock matrix and a positive acid effervescence test.

Fossil-bearing concretion, possibly containing a fossil shell or other organic inclusion

Calcareous concretion; exact fossil and host-rock composition are not identifiable from the image

Fossiliferous Sedimentary Rock

Sedimentary limestone with invertebrate fossil imprint

Sandstone or Siltstone

Arenite (if sandstone)

Sandstone

Arenite

Shale

Shale (clastic sedimentary rock)

Shale (or Mudstone/Siltstone)

Sedimentary Mudrock (SiO2, Al2O3 base with clay minerals)