Values of magnetic susceptibility and natural remanent magnetization (NRM) of clinopyroxene‐garnet‐plagioclase granulite facies lower crustal xenoliths from a kimberlite in west Africa are correlated to bulk geochemistry and specific gravity. Thermomagnetic and AF demagnetization analyses identify magnetite (Mt) and native iron (Fe) as the dominant magnetic phases (totalling ≤0.1 vol.% of the rocks) along with subsidiary sulfides. Oxidation states of the granulites are ≤MW, observed Mt occurs as rims on coarse (∼1 µm) Fe particles, and inferred SD‐PSD Mt may be a result of oxidation of fine‐grained Fe. The deepest limit of lithospheric ferromagnetism is 95 km, but a limit of 70 km is most reasonable for the West African Craton and for modelling Magsat anomalies over exposed Precambrian shields. Copyright 1988 by the American Geophysical Union.
