Question: how many different types of volcanic rocks are there

Jess Wade answered on 15 Jun 2015:

IGneous rock forms from the earth’s mantle from all of the hot magma that is whirling around. Igneous rocks don’t have any fossils inside them but do have lots of bubbles. Different types of volcanoes (depending on their shapes) make different tyes of rocks. Rocks like ‘basalt’, whcih make up the majority of the Earth’s crust, are from shield volcanoes. These form from magma at 1,200 C, which is super hot, and are made of magneisum and iron. There are lighter colour rocks called andesite which form when the magma is a bit cooler (1000 C) from cone shaped volcanoes. They have less iron inside them. There are also white volcanic rocks that have not much magneisum or iron in called rhyolite. They form at low temperatures (750 C). We were aksed a question before about rocks that float. Pumice or ‘pommie’ stones float. They are pushed out of volcanoes at really high pressures and contain 90 % space!