Trachyandesite is one of the important type of rocks. If we have to define Trachyandesite in general, Trachyandesite is an extrusive igneous rock.. Trachyandesite comes under . All Igneous Rocks have similar properties and formation process. Along with Trachyandesite Definition, know more about the History of Trachyandesite, Etymology of Trachyandesite in next sections.