Porphyritic Texture

Porphyritic texture is an igneous rock texture in which large crystals are set in a finer-grained or glassy groundmass. Porphyritic textures occur in coarse, medium and fine-grained igneous rocks. Usually the larger crystals, known as phenocrysts, formed earlier in the crystallisation sequence of the magma. A porphyritic texture in which there is a continuous variation in crystal size is termed seriate. Hypabyssal rocks with porphyritic textures are sometimes termed porphyrys.

Bibliography



• E. WM. Heinrich (1956): Microscopic Petrografy. Mcgraw-hill book company,inc
• David Shelley (1983): Igneous and metamorphic rocks under the microscope. Campman & Hall editori.
• Cox et al. (1979): The Interpretation of Igneous Rocks, George Allen and Unwin, London.

Photo
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Leucite and clinopyroxene crystals in a tephrite from Vulsini (Italy). PPL image, 2x (Field of view = 7mm)
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Leucite crystal wit clinopyroxene inclusions in a tephrite from Vulsini (Italy). PPL image, 2x (Field of view = 7mm)
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Leucite and clinopyroxene crystals in a tephrite from Vulsini (Italy). PPL image, 2x (Field of view = 7mm)
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Plagioclase, biotite and clinopyroxene in a dacite from Bulgaria. XPL image, 2x (Field of view = 7mm)
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Plagioclase, biotite and clinopyroxene in a dacite from Bulgaria. PPL image, 2x (Field of view = 7mm)
dacitebulgaria(3).jpg

Plagioclase, biotite and clinopyroxene in a dacite from Bulgaria. XPL image, 2x (Field of view = 7mm)
dacitebulgaria(4).jpg

Plagioclase, biotite and clinopyroxene in a dacite from Bulgaria. PPL image, 2x (Field of view = 7mm)
dacitebulgaria(5).jpg

Plagioclase, biotite and clinopyroxene in a dacite from Bulgaria. XPL image, 2x (Field of view = 7mm)
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Plagioclase, biotite and clinopyroxene in a dacite from Bulgaria. PPL image, 2x (Field of view = 7mm)