GEOLOGY

Detailed explanation-1: -Rhyolite is light-coloured or white – this is a clue that the rock contains a lot of silica (more than 70%) and not much iron or magnesium. Pumice, a rhyolite, is very common in the central North Island. It may still have evidence of the bubbles of gas trapped as the rock solidified.

Detailed explanation-2: -Magma that is high in silica produces light-colored lava that is too sticky to flow very far; ex. Rhyolite. The less silica magma contains, the lower its viscosity. Low-silica magma flows readily and produces dark-colored lava; ex.

Detailed explanation-3: -Rocks that form light-colored lava or volcanic rocks are called rhyolite. Rhyolite magma usually forms calderas (volcanic craters) and can also form cone volcanoes. It is light colored or white and contains a lot of silica while containing very little magnesium and iron.

Detailed explanation-4: -Felsic magmas are higher in silica and have lighter-colored minerals such as quartz and orthoclase feldspar.

Detailed explanation-5: -Magma that has a higher viscosity and silica content produces rocks that are called rhyolite and andesite.