Obsidian can also be formed when the lava flow meets water or solidifies in the air. These locations include the edge of a lava flow or a lava dome as viscous lava slowly pours out of the mouth of the volcano. Obsidian can be formed in several different locations around lava. When a volcano erupts and lava gushes forth to abruptly meet with a cooling element. When the mineral cristobalite is encased in the obsidian, it results in a rock with mottled white patches in the dark obsidian as seen above in the example of snowflake obsidian. Many variations of obsidian exist, and their appearance depends on the inclusion of impurities, such as iron which leads to dark brown or black obsidian. Obsidian is primarily made of silica, not unlike black tourmaline, but due to the fact that the obsidian forms quickly from the cooling lava, there is no time for a crystalline structure to form, resulting in the amorphous black glass called obsidian. An amorphous solid is not highly ordered in internal structure, unlike a crystal. This is because glass is amorphous, not crystalline in structure. A type of igneous rock, called extrusive igneous rock, obsidian is extruded from the Earth as lava which when rapidly cooled forms a natural glass.Īs a volcanic glass, obsidian is mineral-like, or mineraloid, but is not a true mineral. Obsidian, or lapis obsidianus, is essentially dark glass. Obsidian is an ancient rock that was discovered in Ethiopia by a Roman explorer named Obsidius. Obsidian is a natural glass formed by the meeting of lava from an erupting volcano with cold air or water, imbuing obsidian with all four elements: earth, fire, water, and air.
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