In petrography, the texture (sometimes called structure) of a rock characterizes the arrangement of the crystals between them at the scale of the sample, the thin slice or even on a finer scale.
Texture is a characteristic determined by the size, shape and disposition of minerals in a rock that is observed at the microscopic scale. It allows to build the relationship between these characteristics and the conditions of formation of a rock (especially in the case of magmatic rocks, the rate of cooling).
and Methane 