Search for extractable fullerenes in clays from the Cretaceous/Tertiary boundary of the Woodside Creek and Flaxbourne River sites, New Zealand

When fullerenes were first discovered to form spontaneously in condensing carbon vapors ( Kroto et al., 1985), it was suggested that they might be widely distributed in the Universe. Searches for fullerenes in meteorites (see Devries et al., 1993) were unsuccessful, but C 60 and C 70 were reported to occur on Earth in samples of shungite, a meta-anthracite from a deposit near Shunga, Russia ( Buseck et al., 1992), and in “fulgurite”, a substance formed when lightning strikes certain soils or rocks ( Daly et al., 1993). The occurrence of fullerenes in shungite is particularly surprising since fullerene synthesis in the laboratory has always involved gas phase chemistry at temperatures over 1000°C. Such conditions may be attained during lightning strikes, but shungite is believed to have formed from carbonaceous material creeping into fissures of a Precambrian rock which metamorphosed under extreme pressures. If the original carbonaceous material did not already contain fullerenes perhaps from wildfires, they must have formed during the metamorphism by as yet unknown solid- or liquid-phase mechanisms.