Texture formation in multi-component systems

The mechanisms operating in the formation of textures seen in polycrystalline aggregates of the same species have been discussed in Sections 8.1-8.4. This may correspond to the analysis of a mechanism controlling the so-called selforganization or self-assemblage. Other mechanisms are possible for example, tiny spherical particles are assembled and a close-packed structure is formed due to surface tension. The formation of opal consisting of a close-packed structure of minute amorphous silica spheres maybe such a case. 

In this section, we shall analyze the factors controlling the formation of the texture and structure of polycrystalline aggregates of multiple phases seen in 

Examples are shown in Figs. 8.8(a) and (b), in which the above relations obtained in the industrial crystallization field are applied to crystals in igneous rocks formed 

Sedimentary rocks are composed of epigenetic minerals that have survived weathering and authigenic minerals formed in situ from low-temperature aqueous solution. Since authigenic minerals are formed from aqueous solution at low temperature, they are either amorphous or minute crystalline, and so the texture of sedimentary rocks is principally determined by the sizes and forms of epigenetic minerals. 

In regional metamorphic rocks and contact metamorphic (metasomatic) rocks, new mineral crystals grow in solid rocks in which there was a change in conditions. However, the process is not the same as straightforward solid state growth or recrystallization. Since volatile components such as H O and CO, which were originally present in the rock, are involved, it is better to assume a 

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