Norite is amaficintrusiveigneous rock composed largely of thecalcium-richplagioclaselabradorite, orthopyroxene, andolivine. The namenorite is derived from Norway, by its Norwegian nameNorge.^[1]

Norite, also known asorthopyroxenegabbro, may be essentially indistinguishable from gabbro withoutthin section study under thepetrographic microscope. The principal difference between norite and gabbro is the type ofpyroxene of which it is composed. Norite is predominantly composed of orthopyroxenes, largely high-magnesianenstatite or an iron-bearinghypersthene. The principal pyroxenes in gabbro areclinopyroxenes, generally iron-richaugites.^[2][3]

Norite occurs with gabbro and other mafic toultramafic rocks inlayered intrusions which are often associated withplatinumorebodies such as in the Bushveld Igneous Complex inSouth Africa, theSkaergaard igneous complex ofGreenland, and theStillwater igneous complex inMontana. Norite is also the basal igneous rock of theSudbury Basin complex inOntario, which is the site of acomet impact and the world's second-largestnickel mining region.^{[4][5][6][7][8]}

Norite is a common rock type of theApollo samples. On a smaller scale, norite can be found in small localizedintrusions such as theGombak norite inBukit Batok,Singapore. It is also plentiful in theSokndal intrusion area of southwestern Norway, withtitanium deposits to the east.^[9]

• Igneous petrology
• Mafic rocks

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