directive texture

Directive texture refers to a preferred orientation of platy, tabular, or elongated mineral grains within a rock, creating planar or linear arrangements. This texture is typically a result of magmatic flowage during the rock's formation. It is a characteristic feature of metamorphic rocks, where it is often referred to as foliation. Foliation involves the alignment of mineral grains along straight or wavy planes, which can be parallel to the original bedding of the rock or unrelated to it. This preferred orientation is a key aspect of a metamorphic rock's texture, distinguishing it from rocks with random crystal arrangements.123