Figure 6. The ¹³C CP/MAS NMR spectra for various hydrates (Uchida et al., 1997). A. Leg 164 methane hydrate (this study). B. Natural gas hydrate obtained from the Gulf of Mexico. C. Synthetic gas hydrate (Structure II) enriched with ¹³C methane and propane. D. Synthetic methane hydrate (Structure I) enriched with ¹³C methane. Parts B, C and D are derived from Ripmeester and Ratcliffe (1988).