The first stage of naming an igneous rock is determining whether it is phaneritic or aphanitic. The next step involves the determination of its mineral constituents. The chemical composition of magma is closely related to how explosive and hazardous a volcanic eruption will be. The variation in the amount of silica (Si02) in igneous rocks is used to describe the variation in composition of igneous rocks and the magmas that formed them, as shown in the table "Names of Igneous Rocks Based on Silica Content and Texture." Rocks with low amounts of silica (basalt, gabbro) are known as mafic rocks, whereas rocks with high concentrations of silica (rhyolite, granite) are silicic or felsic rocks.
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Preparing for Armageddon, Natural Disasters, Nuclear Strikes, the Zombie Apocalypse, and Every Other Threat to Human Life on Earth. Most of us have thought about how we would handle various types of scenarios that could signal the end of the world. There are plenty of movies on the subject, psychological papers, and even survivalists that are part of reality TV shows. Perhaps you have had dreams about being one of the few left and what you would do in order to survive.