Norite
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Norite is a mafic intrusive igneous rock composed largely of the calcium-rich plagioclase labradorite and hypersthene with olivine. Norite is essentially indistinguishable from gabbro without thin section study under the petrographic microscope. It occurs with gabbro and other mafic to ultramafic rocks in layered intrusions which are often associated with platinum orebodies such as in South Africa, the Skaergaard igneous complex of Greenland, and the Stillwater igneous complex in Montana, USA. Norite is also the basal igneous rock of the Sudbury Basin complex in Ontario which is the site of a meteorite impact and the world's second largest nickel mining region. Norite is a common rock type of the Apollo samples. On a smaller scale, norite can be found in small localized intrusions such as the Gombak Norite in Bukit Gombak, Singapore.
