Norite typically occurs as discrete intrusive masses or as layers in large, basic intrusions of other materials, as do gabbros, and the two cannot generally be distinguished from one another without the aid of a microscope. A particularly significant intrusion of norite can be found in Ontario, Canada. In fact, a cavity more than 30 meters deep has been excavated from this gigantic mass of rock in order to house the Sudbury Neutrino Observatory, which was designed to facilitate the detection of the elusive neutrino particles emitted from the core of the sun and exploding stars. The location was chosen for this one-of-a-kind building because the norite exhibits a relatively low level of radioactivity and acts as a natural shield, therefore, helping to ensure the unobstructed observation of neutrino events.