Here's why:
* Dacite is an extrusive igneous rock, meaning it is formed from volcanic eruptions. It is characterized by a silica content between 63% and 68%, making it intermediate in composition between andesite and rhyolite.
* Mount Pinatubo is known for its explosive eruptions, which are characteristic of magmas with high silica content. The 1991 eruption, one of the largest volcanic eruptions in the 20th century, released a significant amount of dacitic magma.
While other compositions may be present in smaller amounts, dacite is the dominant and most characteristic magma type associated with Mount Pinatubo's eruptions.
