Pearson correlation coefficient values between porosity and Mg/Fe, Ca, and S at various grid sizes (length scales) in the matrix and FGRs. Plotted values are averages, and error bars show the standard deviation (only statistically significant correlations, p < 0.001, are plotted). Mg/Fe is moderately positively correlated, and sulfur is strongly negatively correlated with porosity at most length scales. Calcium shows a weak correlation with porosity, although it trends toward a moderate correlation at larger length scales (∼300 μm).