sedimentary

Limestone with Iron Oxide Staining

Sedimentary Rock (Calcite, CaCO3)

AI-generated identification · may be incorrect

Hardness on Mohs scale ranges from 3 for the calcite matrix to 6-7 for any chert/quartz inclusions; color is typically yellowish-brown to reddish-brown due to iron staining; luster is earthy to dull; crystal structure is microcrystalline or cryptocrystalline; specific gravity is approximately 2.5 to 2.7.

Identified August 6, 2026More sedimentary →

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Physical properties

Formation & geological history

Formed through the accumulation and compaction of organic and inorganic marine sediments, chemical precipitation, and subsequent weathering where groundwater rich in iron oxides percolated through fractures, staining the rock brown.

Uses & applications

Used primarily in construction, aggregate, production of lime and cement, and as a raw material in various industrial applications.

Geological facts

Iron oxide staining in sedimentary rocks like limestone is extremely common and is frequently referred to as limonite or goethite staining, giving the rock its characteristic rusty appearance.

Field identification & locations

Can be identified in the field by its reaction to dilute hydrochloric acid (fizzing due to calcium carbonate) and its characteristic brownish, weathered crust; commonly found in sedimentary basins and quarries worldwide.