Abstract The germanium content of sea water was found to be 0.05 μg/1. The most abundant organisms of sea water do not take up detectable amounts of germanium. Globigerina ooze and siliceous sponges are devoid of germanium. Diatom frustules may contain some 0.4 p.p.m. germanium. The Pacific northeast equatorial eupelagic clays contain 2 p.p.m. germanium in contrast to shelf material and the south equatorial eupelagic clays, which contain 1 p.p.m. germanium. Shelf sediments and pelagic clays have an identical germanium content of 1 p.p.m. for their coarse fractions while the clay-mineral size fraction of the Pacific north-east equatorial eupelagic clays has a germanium content at least twice the value for the same fraction of the Pacific south equatorial pelagic clays, shelf sediments, and standard marine clay minerals which have been reported to contain 1 p.p.m. germanium. The aluminosilicates are primarily responsible for the germanium content of the clays, and partial removal of the element from sea water appears to take place during the hydrogenous growth of such minerals in sea water. The geochemical fractionation of the element between the shelf and deep-sea sediments and their abundant minerals suggests that shelf sediments and the Pacific south equatorial pelagic clays are primarily lithogenous in origin. On the other hand, the Pacific north-east equatorial eupelagic clays have a coarse fraction which is primarily lithogenous in origin and a clay-mineral size fraction which is rich in hydrogenous clay minerals.