SUMMARY In order to obtain data comparable to those of Biscaye (1965) on the Atlantic Ocean, the authors carried out quantitative X‐ray determinations of clay minerals in the sediments of the Indian and Pacific oceans using the Biscayemethod.

Specific Features of Mineralogy 831 Methods Used in Mineralogical Analysis 834 Methods Used in the Quantitative X-Ray Determination of Quartz and Carbonate Minerals 834 Specific Features of Geochemistry 835 Methods Used in Geochemical Determinations 840 Spectral Method for Determination of Oxides 841 Determination of Chromium, Nickel, Cobalt, Lead, Manganese, Titanium, Zirconium, Copper and Molybdenum By the Spectral Analyses Method 843 X-Ray Diffraction Method for the Study of Clay Minerals 843 Methods for the Determination of Zinc 844 Methods for Determination of Copper and Nickel 845 Methods for Determination of Cadmium, Copper Nickel and Zinc by Atomic Absorption 845 Gamma-Ray Spectrometry 846

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Terrigenous illite, chlorite, kaolinite, and small amounts of vermiculite occur in sediments at the four sites drilled during DSDP Leg 35. Montmorillonite (mix-layered clay), which can result from alteration of volcanogenic material on land and under water, increased and the amount of chlorite plus kaolinite decreased in the older sediments from Sites 322, 323, and 325. The trend in illite content is not well defined.In the Pliocene-lower Miocene age sediments, the crystallization of montmorillonite was more or less constant and increased noticeably only in horizons above the basalts (Sites 322 and 323) as a result of hydrothermal activity. The montmorillonite content increases with depth without a change of its crystallization, perhaps due to the greater influx of montmorillonite into the older sediments, or as the result of postdepositional changes of the clay minerals. This same tendency exists in most oceanic sediments. Other diagenetic but nonclay minerals, clinoptilolite, cristobalite, and goethite, occur in the cores.