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Explain in short Volcanic Rocks
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  • Volcanic rock is an igneous rock of volcanic origin. Volcanic rocks are usually fine-grained or aphanitic to glassy in texture.

  • They often contain clasts of other rocks and phenocrysts. Phenocrysts are crystals that are larger than the matrix and are identifiable with the unaided eye.

  • They were created during fractional crystallization of magma before extrusion. Volcanic rocks are named according to their chemical composition.

  • Basalt is a very common volcanic rock with low silica content.

  • Rhyolite is a volcanic rock with high silica content. Rhyolite has the same chemical composition as granite and basalt is compositionally equal to gabbro.

  • Intermediate volcanic rocks include andesite, dacite, and latite.

  • Volcanic rocks often have a vesicular texture, which is the result voids left by volatiles escaping from the molten lava.

  • Pumice is a rock, which is an example of explosive volcanic eruption. It is so vesicular that it floats in water.

  • Pyroclastic rocks are the product of explosive volcanism. They are usually felsic (high in silica). Examples of pyroclastic rocks are tuff and ignimbrite.

  • Shallow intrusions, which possess structure similar to volcanic rather than plutonic rocks are also considered to be volcanic.

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