Marble is classified as a high-grade metamorphic rock. Its formation occurs when limestone undergoes substantial heat and pressure, transforming its original structure into a denser, more crystalline composition. The metamorphic grade of marble typically reflects the conditions under which it formed.
In geological terms, metamorphic grade indicates the intensity of temperature and pressure conditions that a rock has experienced. For marble, the metamorphic grade is generally considered to be higher than that of many other metamorphic rocks. This is because it typically forms under conditions of moderate to high temperature and pressure, resulting in a resilient and durable stone.
To summarize, marble’s metamorphic grade signifies that it originates from significant geological processes, leading to its unique characteristics and aesthetic appeal often sought after in construction and art.