The main type of rock typically formed at convergent plate boundaries is metamorphic rock. Convergent plate boundaries are areas where two tectonic plates collide, leading to immense pressure and heat being generated in the Earth's crust. This environment is conducive to the transformation of pre-existing rocks through the processes of heat and pressure, resulting in metamorphic rocks.
As the tectonic plates push against each other, sedimentary and igneous rocks that may be present in the crust can undergo metamorphism, changing their mineral composition and texture without melting. This can create various forms of metamorphic rock, such as schist, gneiss, and slate, which often display foliation due to the directional pressure applied during the collision.
While igneous and volcanic rocks can be present in certain tectonic settings, such as subduction zones, the primary product of the intense conditions at convergent boundaries is metamorphic rock. Sedimentary rocks can form from sediments accumulating in layers, but they are not directly formed from the processes occurring at convergent boundaries in their typical manner.