Syenogranite

Syenogranite is a fine to coarse grained intrusive igneous rock of the same general composition as granite.The feldspar component of syenogranite is predominantly orthoclase. Syenogranite is similar to syenite, however the major difference is its higher content of quartz (15-25%) usually at the expense of some alkali feldspar (45-50%), the domination of biotite over hornblende and the presence of muscovite and rutile as additional accessories in the syenogranite.

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
Orthoclase, plagioclase and clinopyroxene (high interference coloros). XPL image, 2x (Field of view = 7mm)	Orthoclase, plagioclase and clinopyroxene (high interference coloros). XPL image, 2x (Field of view = 7mm)	Orthoclase, plagioclase and clinopyroxene (high interference coloros). XPL image, 2x (Field of view = 7mm)
Orthoclase, plagioclase and clinopyroxene (high interference coloros). XPL image, 2x (Field of view = 7mm)	Orthoclase, plagioclase and clinopyroxene (high interference coloros). XPL image, 2x (Field of view = 7mm)	Orthoclase, plagioclase and clinopyroxene (high interference coloros). XPL image, 2x (Field of view = 7mm)