Identifying Non-Metamorphic Rocks

Metamorphic rocks are formed when existing rocks are transformed by heat, pressure, or chemical reactions. We need to identify which option is not formed this way.

Metamorphic Rock Analysis

• Gneiss: This is a high-grade metamorphic rock, often formed from pre-existing sedimentary or igneous rocks under intense heat and pressure.
• Marble: This metamorphic rock is formed when limestone is subjected to heat and pressure, causing its calcite crystals to recrystallize.
• Slate: This is a low-grade metamorphic rock formed from shale or mudstone subjected to low-grade metamorphism.
• Limestone: This is primarily a sedimentary rock. It is formed from the accumulation of organic debris, such as shells and coral, or through chemical precipitation. While limestone can be *transformed* into marble (a metamorphic rock), limestone itself is sedimentary.

Conclusion

Based on the analysis, Limestone is the rock that is not a metamorphic rock.