Yellow Limestone
Non-clastic chemical sedimentary rock
It is usually formed from the precipitation of calcium carbonate (CaCO₃) in calm marine environments. Sometimes it is biochemical if it contains the remains of microscopic marine organisms.
Light yellow to dark yellow. The color results from the presence of impurities of iron oxides (FeO) (Fe₂O₃) or organic matter.
Usually fine to medium crystalline. The fine grains may be the remains of microscopic shells or crystalline carbonates.
Smooth, fine, sub-circular or indistinct. Sometimes organic remains or fine grains of calcite are seen.
The sorting is often unclear, because limestone is not formed from independent granular clasts, but rather from direct chemical or biological precipitation.
Well-compacted to solid. If pure and compacted, it is a strong rock. It is sometimes used in construction and sculpture.
→ CaCO₃ Calcium carbonate (the main component of limestone)
It is most often formed in: warm, shallow seas, reef or lagoon environments,
or in biological sedimentation environments rich in microorganisms.
If exposed to high heat and pressure, it turns into marble.
If it contains a percentage of clay, it is called marlstone.