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Carbonate-altered serpentinite (listwanite) is commonly associated with gold mineralization, but also binds large quantities of the greenhouse gas carbon dioxide. At Atlin, listwanite alteration progressed through three carbonation reactions that resulted in the same overall mineral transformations as proposed for the industrial sequestration of anthropogenic CO2 by the process of mineral carbonation. Therefore, alteration of serpentinite to listwanite serves as a natural analogue to CO2 sequestration. Listwanite alteration is concentrated along faults and two orthogonal fracture sets, and extends tens of metres into the wall rock. One fracture orientation is preferentially mineralized. The carbonation reactions most distal to the fracture system consume olivine and brucite, and record grain-scale percolation of CO2-bearing fluids into serpentinite hundreds of metres from visible carbonate alteration. These previously unrecognized reactions may be relevant for in situ CO2 sequestration. Extensive carbonation in the carbonate alteration systems generated fracture permeability that promoted further infiltration and may have accelerated carbonation and gold mineralization.

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Alkari-silica reactions have a harmful effect on some andesites. In the present paper, the alkali -silica reactions in andesitic rocks were examined by means of optical and X-ray diffraction analyses and the standard test with mortar bars (ASTM C227). Furthermore, by the microscopic examination of the dyed thin section made from a mortar bar, various types of reaction products including cracks and spherules were identified and distinguished. The contents of alkari-reactive minerals such as cristobalite, tridymite, and glass, which are present in andesites, are irregular and change very much with the location. The results of the test on mortar bars had no direct correlation with any kind of alkali -reactive minerals . It is difficult to determine the role of these alkali-reactive minerals in the expansive alkali-silica reaction, because there are many factors in the reaction.