EVSC 2800 Chapter Notes - Chapter 4: Volcanic Glass, Metamorphic Rock, Igneous Rock
12 May 2016
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Document Summary
Rocks do not follow this idealistic path every time they go through the rock cycle, they can be transformed to either of the other two groups or be recycled in their own group. Composition of a rock refers to what the rock is made of. Chemical composition refers to the chemical elements that make up the rock. Physical composition of rocks is simply a description of what visible materials they are made up of. Chemical composition determines how the rock will react with materials of different composition. Chemical composition determines rock color (ferromagnesian-rich rocks [iron and magnesium rich rocks] generally have a dark color, ferromagnesian-poor rocks generally have a light color) Glass is an amorphous (meaning it contains no definite form, it is not crystalline) solid that forms by cooling molten materials like melted rock or quartz sand. Rock-forming processes and the rock cycle looks and breaks just like window glass, except it is usually dark colored.
