PORPHYRITIC ROCK Meaning and
Definition
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Porphyritic rock is a type of igneous rock characterized by a distinct texture that exhibits both large, well-formed crystals and smaller crystals or groundmass. The term "porphyritic" derives from the Greek word "porphyra," meaning "purple," a reference to the rock's common association with purple or violet-colored minerals.
The larger crystals, known as phenocrysts, are readily visible to the naked eye and typically possess well-defined crystal faces. These phenocrysts are often composed of minerals like feldspar, quartz, or hornblende, which can range in size from a few millimeters to several centimeters. The groundmass, or matrix, is composed of smaller crystals or fine-grained minerals, which may be of the same or different composition than the phenocrysts.
The formation of porphyritic rock occurs through a two-stage cooling process. Initially, the molten rock or magma cools slowly beneath the Earth's surface, allowing the larger phenocrysts to crystallize and grow. This slow cooling allows the phenocrysts to develop distinct crystal faces. As the remaining molten rock is forced to the Earth's surface during volcanic activity, it cools rapidly, resulting in the formation of the groundmass with smaller crystals.
Porphyritic rock can be further classified based on its mineral composition and texture, with examples including porphyritic granite, porphyritic basalt, and porphyritic rhyolite, among others. These rocks often exhibit a striking appearance due to the contrast between the large phenocrysts and the finer-grained groundmass. Porphyritic rock is commonly used as a building material, as well as being of significant interest to geologists for the insights it provides into the geological processes that occurred during its formation.
Common Misspellings for PORPHYRITIC ROCK
- oorphyritic rock
- lorphyritic rock
- -orphyritic rock
- 0orphyritic rock
- pirphyritic rock
- pkrphyritic rock
- plrphyritic rock
- pprphyritic rock
- p0rphyritic rock
- p9rphyritic rock
- poephyritic rock
- podphyritic rock
- pofphyritic rock
- potphyritic rock
- po5phyritic rock
- po4phyritic rock
- porohyritic rock
- porlhyritic rock
- por-hyritic rock
Etymology of PORPHYRITIC ROCK
The word "porphyritic" is derived from the Greek word "porphyra", meaning purple. It is a term used in geology to describe a specific rock texture in which large crystals, known as phenocrysts, are embedded in a finer-grained matrix or groundmass. The phenocrysts are usually distinctly larger than the surrounding groundmass, creating a contrasting appearance. The term "porphyritic" was first introduced by the Scottish geologist James Hutton in the late 18th century to describe rocks with this particular texture. The name was likely chosen due to the resemblance of some porphyritic rocks, such as porphyry, to the purple color associated with the porphyry stone used in ancient Roman imperial decorations.
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