Métamorphiques

Métamorphiques are a major class of rocks that have undergone transformation from a pre-existing rock type. This transformation, known as metamorphism, occurs due to changes in temperature, pressure, and/or chemical environment. The original rock, called the protolith, can be igneous, sedimentary, or even another metamorphic rock. The process of metamorphism does not involve melting; instead, it recrystallizes minerals and creates new ones within the solid state.

The type of metamorphic rock formed depends on the protolith and the specific conditions of metamorphism. Common metamorphic rocks include marble, formed from limestone; slate, formed from shale; schist, often derived from shale or basalt and characterized by its platy minerals; and gneiss, a high-grade metamorphic rock with distinct banding of light and dark minerals.

Metamorphic rocks are typically found in areas of intense geological activity, such as mountain ranges or the roots of ancient volcanoes. Their textures and mineral compositions provide valuable clues about the pressure and temperature conditions they experienced deep within the Earth's crust. This makes them crucial for understanding geological history and tectonic processes.