What is the small deposits of igneous and metamorphic crystals?

Small deposits of igneous and metamorphic crystals typically refer to mineral assemblages found within volcanic or metamorphic rocks. These crystals form from the cooling and solidification of magma (igneous) or through the alteration of existing rocks under heat and pressure (metamorphic). Common examples include quartz, feldspar, and mica, which can occur in pockets or veins within the host rock. These deposits can be significant for understanding geological processes and are often sought after in mineral exploration.