is an unusual iron
sulfide mineral with a variable iron
content: Fe(1-x)S (x = 0 to 0.2).
The FeS end member is known as triolite.
Pyrrhotite is also called magnetic
pyrite because the color is similar to
pyrite and it is weakly magnetic.
The magnetism increases as the iron
content decreases, and the triolite
is a rather common
trace constituent of mafic igneous rocks
especially norites. It occurs
as segregation deposits in layered
intrusions associated with pentlandite,
chalcopyrite and other sulfides. It is
an important constituent of the
Sudbury intrusion where it occurs in
masses associated with copper and
nickel mineralisation. It also occurs in
pegmatites and in contact metamorphic
zones. Pyrrhotite is often accompanied
by pyrite, marcasite and magnetite.
Pyrrhotite does not have specific
applications. It is mined primarily
it is associated with pentlandite,
sulfide mineral that can contain
amounts of nickel and cobalt.