Classifications of Ni-Cu deposits are based on petrology,
geochemistry and the geotectonic setting of host igneous bodies
(Naldrett and Cabri, 1976; Besson et al, 1979; Nadrett, 1989).
The four major classes in Naldrett's (1989) division rest on the
geotectonic setting of the igneous complexes and the classes are
further subdivided on the basis of the petrology and geochemistry
of the intrusion. A more common subdivision of mafic and
ultramafic igneous rocks is based on the environment of
rock-forming processes, endogenic or exogenic, intrusive or
extrusive, and this subdivision has been applied, in practice, to
the classification of sulphide Ni-Cu deposits, too. The extrusive
deposits, Class I in Naldrett's (1989) classification, are directly
related to volcanic processes whereas all the others refer to the
intrusive environment. This paper looks at the differences between the extrusive and
intrusive groups of Ni-Cu deposits and presents generic, genetic
and structural features of the intrusive group.