MagmaMagma is the term used to describe molten material within the Earth; in simple terms: molten rock. But the molten rock usually contains some suspended crystals or dissolved gases. Igneous rocks form through the crystallization of magma. There is a considerable range of melting temperatures for different compositions of magma.
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Index Igneous rock concepts Data Reference Lutgens & Tarbuck Ch 3 | ||
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Igneous RockMolten material within the Earth is called magma. In simple terms magma can be thought of as molten rock. When magma cools, it solidifies to form rock which is called "igneous rock". That is deceptively simple, since the solidification process can be very complex. There is a considerable range of melting temperatures for different compositions of magma. Upon cooling from the completely molten state, it is typical for silicon tetrahedra to form first, and they in turn join with each other and other ions to form the nuclei for crystal growth. The minerals with the highest melting points will crystalize first, and their crystal growth may continue unimpeded as long as the surrounding material remains molten. Depending upon the surroundings and the rate of cooling, a great variety of textures and compositions of igneous rock can be formed. When crystallization is complete, the result is a solid mass of interlocking crystals of different sizes. |
Index Igneous rock concepts Data Reference Lutgens & Tarbuck Ch 3 | ||
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