Buseck et al.'s (1992) discovery of fullerenes in fractures in a shungite sample (enclosed in diabase) from Russian Karelia has been followed by several substantiating reports (see Buseck, 2002, p. 785) as well as by conflicting reports (e.g., Ebbesen et al., 1995; Mossman et al., 2003) concerning the existence of fullerenes in this unusual carbon-rich rock. Thus, Parthasarathy et al. (1998) reported fullerenes in type I (bright) shungites from the Kondopoga mine in Russian Karelia. In light of Mossman et al.'s (2003) failure to find fullerenes in shungite (including type I shungite) from four different localities in Russian Karelia, Parthasarathy and Vairamani's concern certainly seems justified. Is it possible that, after all, fullerenes do not occur in shungite? In his recent review and analysis of geological fullerenes, even Buseck (2002, p. 784) seems convinced that he and his colleagues “. . . studied an unusual sample.” But a really unusual sample would have to be the dinosaur eggs reported by Wang et al. (1998) to contain fullerenes! That occurrence might well qualify as a bona fide artifact of the analyses.
As Parthasarathy and Vairamani observe, the sampling problem is crucial. At Kondopoga, the quarry exposes a 500-m-thick lacustrine sequence of graywackes deposited from turbidity currents. This sequence caps ~500 m of basalt overlying the major shungite deposits. Indications are (Filippov, 2002, p. 223–228) that all shungite in the lacustrine sequence is clastic. However it was derived, the Kondopoga clastic shungite has not only necessarily been exposed for an extended interval of time, but it may also represent a residue of basalt-affected lustrous shungite not representative of the usual shungite.
Correction to the comment: we did not conclude, as Parthasarathy and Vairamani state, “. . . that natural fullerenes appear to form exclusively in extraterrestrial samples.” The word “almost” appears in the original (Mossman et al., 2003, p. 258) between the words “form,” and “exclusively.” A prime terrestrial candidate for natural fullerenes is Jehliĉka et al.'s (2003) confirmation of earlier work (Jehliĉka et al., 2000) reporting the presence of fullerenes in (two of four) samples of solid bitumen enclosed in Proterozoic pillow lavas from Mítov in the Bohemian Massif. Thereby, the likelihood of encountering fullerenes as by-products of contact metamorphism elsewhere is increased—including some shungite from Russian Karelia.