From Kaufman's Geophysical Field Theory
 

Material	Susceptibility (x 10^6)	Material	Susceptibility (x 10^6)
Quartz	-15	Gabbro	4000-90,000
Graphite	-100	Dolomite	20000
Anhydrite	-14	Pyrite	50
Marble	-9	Hematite	400-10,000
Basalt	1500-20,0000	Magnatite	10^7