Magma is molten rock and varies greatly in composition. Magma can contain varying amounts of iron, magnesium, calcium, silicon, potassium, aluminum, oxygen, sulfur, manganese, copper, uranium, and a...
It is really stupid.
its made up of silica ,water ,and gas content of magma
Krakatoa is made up of these 2 magma's " Brimetic and Basaltic.
Then, Earth would have been geologically dead.