Rocks such as serpentine, slate, soapstone, and marble belong to which class of rocks?

The classification of rocks is based on their formation processes, and the rocks listed—serpentine, slate, soapstone, and marble—are all formed through metamorphism.

Metamorphic rocks are created when existing rocks are subjected to intense heat, pressure, or chemically active fluids, transforming their mineral composition and structure without melting. For instance, slate originates from shale under pressure, and marble comes from limestone that has been metamorphosed. Serpentine forms from the alteration of ultramafic rocks, and soapstone is primarily composed of talc, which is also a product of metamorphic processes.

This metamorphic origin distinguishes these rocks from igneous rocks, which crystallize from cooled magma or lava, or sedimentary rocks, which are formed from the accumulation and lithification of sediment. The classification as a carbonate rock typically refers specifically to sedimentary rocks composed mainly of carbonate minerals, such as limestone or dolomite, which does not apply to the rocks listed. Hence, recognizing that serpentine, slate, soapstone, and marble fit within the metamorphic category is essential for understanding their formation and properties.