Igneous rocks have several distinct characteristics. Here are four key ones:
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Mineral Composition: Igneous rocks are primarily composed of minerals such as quartz, feldspar, and mica. The specific mineral composition can vary widely, leading to different types of igneous rocks, such as granite (coarse-grained) and basalt (fine-grained).
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Texture: The texture of igneous rocks can vary depending on the cooling rate of the magma or lava. Slow cooling results in larger crystals (coarse-grained texture), while rapid cooling results in smaller crystals (fine-grained texture). Some igneous rocks can also exhibit a glassy texture, indicating extremely rapid cooling (e.g., obsidian).
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Formation Process: Igneous rocks are formed from the solidification of molten rock material (magma or lava). They can form either beneath the Earth's surface (intrusive igneous rocks) or on the surface as a result of volcanic activity (extrusive igneous rocks).
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Color: The color of igneous rocks can vary widely depending on their mineral content. Generally, rocks rich in silica, like granite, tend to be lighter in color (often pink or gray), while those with lower silica content, like basalt, are typically darker (often black or dark gray).
These characteristics help geologists classify and differentiate between various types of igneous rocks.