Here's why:

* Formation: Pegmatites form from the crystallization of magma (molten rock) deep within the Earth. They are essentially the final stages of magma cooling, where the remaining fluids are very rich in water and volatiles.

* Large Crystals: Pegmatites are known for their extremely large crystals, often visible to the naked eye. This is due to the slow cooling and abundance of water in the magma, allowing the crystals to grow unimpeded.

* Composition: They are typically composed of feldspar, quartz, mica, and other minerals found in igneous rocks.

Metamorphic rocks form when existing rocks are transformed by heat, pressure, or chemical reactions. Pegmatites, on the other hand, form directly from magma, making them igneous rocks.

While pegmatites can be found in metamorphic settings, their origin is still igneous. They are often associated with metamorphic rocks because the intense heat and pressure involved in metamorphism can contribute to the formation of pegmatites.