Tachylite is one of the important type of rocks. If we have to define Tachylite in general, Tachylite is a vitreous form of basaltic volcanic glass. This glass is formed naturally by the rapid cooling of molten basalt. Tachylite comes under Igneous Rocks. All Igneous Rocks have similar properties and formation process. Along with Tachylite Definition, know more about the History of Tachylite, Etymology of Tachylite in next sections.