3.4.4 Igneous Textures: Glassy Texture Rocks, Obsidian from Granite and Basalt
Channel: Snow Mountain
Date: 2020-09-21

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3.4.4 Igneous Textures: Glassy Texture Rocks, Obsidian from different magma compositions Granite and Basalt 

Glassy texture. During some volcanic eruptions, molten rock is ejected into the atmosphere where it is quenched quickly. Rapid cooling of this type may generate rocks having a glassy texture. Glass results when unordered ions are frozen before they are able to unite into an orderly crystalline structure.

Obsidian, a common type of natural glass, is similar in appearance to a dark chunk of manufactured glass. Because of its excellent conchoidal fracture and ability to hold a sharp, hard edge, obsidian was a prized material from which Native Americans chipped arrowheads and cutting tools. Today, scalpels made from obsidian are being used for delicate plastic surgery because they leave less scarring than those made of steel.


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