Fluids and Rocks - Introduction to Carbon Capture and Sequestration - page 448

Figure 9.8.10 Surface coatings and amorphous phases
Illustration of the formation of surface coatings and amorphous phases during silicate
weathering. The fi gure on the left side shows a calcite coating formed on the surface of
a fast-dissolving silicate (wollastonite, CaSiO 3 ) upon exposure to CO 2 -rich water at
pH 6 and 90°C. The fi gure on the right side shows an amorphous gel layer formed on a
feldspar surface during dissolution at low pH. Geochemical models generally neglect the
existence of these surface coatings and amorphous solid phases. Images reproduced
from Daval et al. [9.43] and Casey et al. [9.44], both with permission from Elsevier.