Norite
“Gabbro's pyroxene-rich twin”
Norite is a coarse-grained mafic intrusive rock very similar to gabbro but distinguished by its dominant orthopyroxene rather than clinopyroxene. It forms in large layered intrusions and is famously associated with some of the world's richest nickel and platinum deposits.
orthopyroxene (hypersthene), plagioclase feldspar, olivine (minor), chromite
Sudbury Basin (Ontario, Canada), Bushveld Complex (South Africa), Bergen (Norway), Duluth Complex (Minnesota, USA)
6-6.5
The Sudbury norite was formed by a massive asteroid impact 1.85 billion years ago — the resulting melt sheet created one of the world's largest nickel-copper ore deposits.
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