Figure 5. (A) Total porosity and (B) percent of total porosity with aspect ratios <0.1 vs. grain density. A least-squares-fit (solid line) is shown along with one standard deviation bounds (dashed lines) for (A) and (B). The standard deviations for the fits to (A) and (B) are 0.75% and 5.2%, respectively. Again, grain density is indicative of the relative amount of alteration products, with lower grain densities reflecting a higher percentage of alteration products. These results show a trend toward a lower percentage of thin cracks present in the more altered samples, even though the bulk porosity is higher in these samples. This relationship suggests that the thin cracks are the first pores to be filled by alteration.