Fig. 1 The ratio (R) of EGME area to the crystallographic surface area, derived from the unit cell weight and b-axis parameter, in relation to the ratio of tetrahedral sheet charge to total charge for 25 smectites. The numbers in parentheses are the charge per unit cell based on total chemical analysis. The asterisk denotes those samples for which no impurities are reported (Table 1, Low, 1980). Sample 23 is Wyoming montmorillonite* (0.76) and the other samples are: 1. Aberdeen* (0.75), 2. Argentine* (0.69), 3. Belle Fourche* (0.67), 4. Blue Western* (0.65), 5. Cameron (1.21), 6. Czechoslovakia 1 (0.68), 7. Czechoslovakia 650 (0.69), 8. Danish (0.43), 9. Guam (0.58), 10. High Grade Western* (0.72), 11. India (0.76), 12. Italian* (0.89), 13. Louisiana (0.53), 14. Monte Amiata (1.44), 15. New Mexico* (0.97), 16. New Zealand (0.75), 17. Otay* (1.25), 18. Polkville* (1.07), 19. Romanian (0.71), 20. Sardinian (0.91), 21. Smithville (0.80), 22. Texas* (0.78), 24. Western Ca* (0.81), 25. Yellow Western (0.60)
