Table 4 Pearson correlation coefficient between all combinations of microdensity variables (width = ring width; m = mean ring density; mi = minimum ring density; ma = maximum ring density; rsd = ring density standard deviation) and ring porosity index

−0.31^c

−0.34^c

0.71^c

−0.07^a

0.76^c

0.36^c

−0.19^c

Ns

−0.47^c

0.37^c

−0.29^c

Ns

0.53^c

0.17^c