Abstract
The results of two types of dissolution experiment were reexamined to elucidate the influence of specific factors on the dissolution characteristics of granitic rocks (granodiorite and granite). Experiment A involved various solid/liquid ratios (0.25, 0.5, and 1) using samples (200 g in weight) crushed into fragments with three types of grain size (diameter of 32–45 mm, 8–16 mm, and 1–2 mm). In experiment B, a clay-sized powder sample (1.0 g in weight) or a block sample (3.54×3.54×20 mm3) was treated with 50. 0 ml of distilled water. The results of the experiments showed that 1) the dissolution characteristics (dissolution rate and amount of dissolved materials) are affected by the solid/liquid ratio and surface area of crushed samples, and the characteristics of granite are strongly influenced by the surface area; and 2) the difficulty dissolving a mass of granite is caused by the low porosity and small amount of alkali elements. Based on this evidence, one of key factors in the dissolution characteristics of granite is the behavior of colored minerals. When a mass of granite is crushed, Fe, K, and Mg are easily leached from the edge of biotite crystal, which influences the surface area and thus dissolution characteristics.
