We have analyzed Sb in a variety of mantle-derived volcanic rocks, per
idotites, and in the CI chondrite Orgueil by spark source mass spectro
metry. Concentrations vary from 0.02 to 0.8 ppm in oceanic basalts (mi
d-ocean ridge basalts, MORB; oceanic island basalts, OIB). Antimony is
a moderately;siderophile element which behaves like the incompatible
lithophile element Pr during igneous processes in the mantle. Both MOR
B and OIB samples have similar Sb/Pr ratios of about 0.02, which are d
ifferent from those in continental-crustal rocks. Antimony resembles P
b in that it behaves like a highly incompatible element during formati
on of continental crust, whereas it behaves only moderately incompatib
le during formation of oceanic basalts (MORB or OIB). Consequently, Sb
/Pb ratios of oceanic basalts agree within error limits with those of
the continental crust and with the CI chondritic value, indicating tha
t Sb/Pb is not strongly fractionated during crust-mantle-core differen
tiation. From the Sb/Pb ratios we estimate a Sb concentration of 11 +/
- 5 ppb for the primitive mantle. An alternative estimate for the prim
itive-mantle abundance is obtained by assuming the Sb/Pr ratio of the
primitive mantle to be intermediate between the MORB-OIB value (0.02)
and that of the continental crust (0.05). This approach yields Sb = 8
+/- 4 ppb for the primitive mantle. Antimony is depleted in the bulk s
ilicate Earth by a factor of 45. The volatility-corrected depletion fa
ctor of 7 is similar to other moderately siderophile elements. (C) 199
7 Elsevier Science B.V.