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Table 3 Comparison of the physical and geological characteristics of the two divalent cations under study as putative signs in this paper

From: Empirical demonstration of environmental sensing in catalytic RNA: evolution of interpretive behavior at the origins of life

Chemical properties

Modern conditions

Early life conditions

Cation

Hydration number

Ionic radius (Å)

pK a

Hardness (η c)

Oceans (mM)

Cells (mM)

Archaean ocean (%)

Hydrothermal vents (mM)

Affinity for montmorillonite clay ( k a/ k Cd)

Mg2+

6

0.72

11.42

47.59

50

30

24

51

0.9

Ca2+

8

1.12

12.70

19.52

10

1

29

232

5.8

  1. Data taken from references [15]-[18].