抄録
Fig Tree shale, one of the early Archean sediments occurred in the Swaziland System in South Africa, was examined for clay minerals. These minerals found in the shale are chlorite and illite with chlorite predominance. The chlorite is a typical Mg-, Fe-chlorite and is likely the IIb polytype. The illite could not be specified as to its polytype. An examination by an analytical electron microscope of individual particles reveals that the chlorite is fairly uniform in chemical composition, whereas the illite may vary to phengite. The chlorite and illite are probably formed during the burial diagenesis, considering the shale's age 3 billion years old. These two clay minerals are perhaps the oldest terrestrial clay minerals that are identified and characterized chemically.
