A traverse across Precambrian rocks from the Kapuskasing uplift in Ontario provided 31 samples from a crustal cross section that is now exposed at the surface. About half the samples are dominantly paramagnetic. Magnetite, accompanied in a few samples by minor amounts of pyrrhotite, is the only significant magnetic mineral in the other half; magnetic susceptibilities of these samples are constant between room temperature and about 540 ¿C, above which temperature they drop rapidly to zero. Magnetic susceptibility does not depend on rock type, apparent original depth in the crust, or degree of metamorphism. The average induced magnetization of the most magnetic units in this section is less than 1 A/m, which is much lower than the source requirements for the deep crust deduced from aeromagnetic and satellite magnetometer surveys. ¿ American Geophysical Union 1988