What is rocks formed from a new substances?

Rocks formed from new substances are typically referred to as "metamorphic rocks." These rocks are created when existing rocks—igneous, sedimentary, or even other metamorphic rocks—undergo significant changes due to extreme heat, pressure, or chemically active fluids. This process, known as metamorphism, alters the mineral composition and structure of the original rock, resulting in new minerals and textures. Examples of metamorphic rocks include schist, gneiss, and marble.