How do igneous rocks wiht glassy textures form?
giorgiana1976 Teacher Doctorate eNotes Editor Glass is found in nature as volcanic material (obsidian) and the form of misterious objects, known as tektites. Often volcanic lava was poured into water lakes or oceans, and from this contact has suffered a rapid cooling process, which led to the rocks results of a glassy texture. Obsidian is amorphous and translucent. The presence of iron and magnesium gave obsidian a dark green color to black. Tektites have a variable chemical composition, but the one is based on silica glass with impurities of magnesium, iron and other elements. Tektites form is special, being irregular, presenting various lumps and bulbs of glassy substance. These gems are not volcanic in nature. Their chemical composition has not yet been explained. There are theories that had emerged from tektites meteoric impact which occurred with their formation, at extremely high temperatures and pressures; tektites are actually bodies of molten glass formed from a contact betwee
