Norite

Norite is a coarse-grained basic igneous rock dominated by essential calcic plagioclase and orthopyroxene. The name Norite is derived from the Norwegian name for Norway: Norge. Norite may be essentially indistinguishable from gabbro without thin section study under the petrographic microscope. The principal difference between norite and gabbro, however, is the type of pyroxene of which it is composed; norite is predominately composed of orthopyroxenes, largely high magnesian enstatite or an iron bearing intermediate hypersthene, whereas the principal pyroxenes in gabbro are clinopyroxenes, generally medially iron-rich augites. Norite occurs with gabbro and other mafic to ultramafic rocks in layered intrusions which are often associated with platinum orebodies such as in the Bushveld Igneous Complex in South Africa, the Skaergaard igneous complex of Greenland, and the Stillwater igneous complex in Montana, USA. .

Norite (labradorite and hypersthene with olivine) from the Bushveld Upper Zone, South Africa. Keele Collection. From Ian Geoffrey Stimpson

Norite. Upper Main Zone, Bushveld Complex, South Africa. Keele Collection. From Ian Geoffrey Stimpson

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 and orthopyroxenes in a Norite from Germany. PPL image, 2x (Field of view = 7mm)	Plagioclase and orthopyroxenes in a Norite from Germany. XPL image, 2x (Field of view = 7mm)	Plagioclase and orthopyroxenes in a Norite from Germany. PPL image, 2x (Field of view = 7mm)
Plagioclase orthopyroxenes and clinopyroxene (stronger birefringence) in a Norite from Germany. XPL image, 2x (Field of view = 7mm)	Plagioclase and orthopyroxenes in a Norite from Germany. PPL image, 2x (Field of view = 7mm)	Plagioclase and orthopyroxenes in a Norite from Germany. XPL image, 2x (Field of view = 7mm)
Plagioclase and orthopyroxenes in a Norite from Germany. PPL image, 2x (Field of view = 7mm)	Plagioclase and orthopyroxenes in a Norite from Germany. XPL image, 2x (Field of view = 7mm)	Plagioclase and orthopyroxenes in a Norite from Germany. PPL image, 2x (Field of view = 7mm)
Plagioclase and orthopyroxenes in a Norite from Germany. PPL image, 2x (Field of view = 7mm)	Plagioclase and orthopyroxenes in a Norite from Germany. XPL image, 2x (Field of view = 7mm)	Plagioclase and orthopyroxenes in a Norite from Germany. PPL image, 2x (Field of view = 7mm)
Plagioclase orthopyroxenes and clinopyroxene (stronger birefringence) in a Norite from Germany. XPL image, 2x (Field of view = 7mm)	Plagioclase and orthopyroxenes in a Norite from Germany. PPL image, 2x (Field of view = 7mm)	Plagioclase orthopyroxenes and clinopyroxene (stronger birefringence) in a Norite from Germany. XPL image, 2x (Field of view = 7mm)
Plagioclase and orthopyroxenes in a Norite from Germany. PPL image, 2x (Field of view = 7mm)	Plagioclase and orthopyroxenes in a Norite from Germany. XPL image, 2x (Field of view = 7mm)	Plagioclase and orthopyroxenes in a Norite from Germany. PPL image, 2x (Field of view = 7mm)
Plagioclase orthopyroxenes and clinopyroxene (stronger birefringence) in a Norite from Germany. XPL image, 2x (Field of view = 7mm)	Plagioclase and orthopyroxenes in a Norite from Germany. PPL image, 2x (Field of view = 7mm)	Plagioclase and orthopyroxenes in a Norite from Germany. XPL image, 2x (Field of view = 7mm)
Plagioclase and orthopyroxenes in a Norite from Germany. PPL image, 2x (Field of view = 7mm)	Plagioclase and orthopyroxenes in a Norite from Germany. XPL image, 2x (Field of view = 7mm)	Plagioclase and orthopyroxenes in a Norite from Germany. XPL image, 2x (Field of view = 7mm)