Hypocrystalline texture

Hypocrystalline is a textural term describing an igneous rock consisting of a mixture of glass and crystals where the ratio of crystals to glass is greater than 3:5. Rocks containing a higher ratio of glass are described as hypohaline or holohyaline. Usually devitrified glass is treated as glass in the classification of hypohyaline rocks.

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
Plagioclase (with sieve texture) in an andesite with hypocrystalline groundmass. XPL image , 2x (Field of view = 7mm)	Plagioclase (with sieve texture) in an andesite with hypocrystalline groundmass. PPL image , 2x (Field of view = 7mm)	Plagioclase (with sieve texture) in an andesite with hypocrystalline groundmass. PPL image , 2x (Field of view = 7mm)
Plagioclase (with sieve texture) in an andesite with hypocrystalline groundmass. PPL image , 2x (Field of view = 7mm)	Plagioclase (with sieve texture) in an andesite with hypocrystalline groundmass. XPL image , 2x (Field of view = 7mm)	Plagioclase (with sieve texture) in an andesite with hypocrystalline groundmass. PPL image , 2x (Field of view = 7mm)
Plagioclase (with sieve texture) in an andesite with hypocrystalline groundmass. XPL image , 2x (Field of view = 7mm)	Plagioclase in an andesite with hypocrystalline groundmass. PPL image , 10x (Field of view = 2mm)	Plagioclase (with sieve texture) in an andesite with hypocrystalline groundmass. PPL image , 10x (Field of view = 2mm)