出典:Wikipedia
出典:『Wikipedia』 (2011/04/03 18:19 UTC 版)
Tachylite (also spelled tachylyte) is a vitreous form of basaltic volcanic glass. This "glass" is formed naturally by the rapid cooling of molten basalt. It is a basic type of igneous rock that is decomposable by acids and readily fusible. The color is a black or dark-brown, and it has a greasy-looking, resinous luster. It is very brittle and occurs in dikes, veins and intrusive masses.