What is Rhyolite?

Rhyolite is an igneous rock. It can also be considered as the extrusive equivalent to the plutonic granite rock, and consequently, broken rhyolite may bear a same resemblance as granite. Due to the high concentration of silica and low iron and magnesium contents, rhyolite melts are highly polymerized and form highly viscous lavas.

They also occur as breccias or in volcanic plugs and dikes. Obsidian is when rhyolites melt and cool too quickly to grow crystals form a natural glass or vitrophyre. Slower cooling of rhyolites forms microscopic crystals in the lava and gives its results in textures such as flow foliations, spherulitic, nodular, and lithophysal structures.