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

• Cox et al. (1979): The Interpretation of Igneous Rocks, George Allen and Unwin, London.
• Howie, R. A., Zussman, J., & Deer, W. (1992). An introduction to the rock-forming minerals (p. 696). Longman.
• Le Maitre, R. W., Streckeisen, A., Zanettin, B., Le Bas, M. J., Bonin, B., Bateman, P., & Lameyre, J. (2002). Igneous rocks. A classification and glossary of terms, 2. Cambridge University Press.
• Middlemost, E. A. (1986). Magmas and magmatic rocks: an introduction to igneous petrology.
• Shelley, D. (1993). Igneous and metamorphic rocks under the microscope: classification, textures, microstructures and mineral preferred-orientations.
• Vernon, R. H. & Clarke, G. L. (2008): Principles of Metamorphic Petrology. Cambridge University Press.

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