Granulite is described as having which level of foliation?

• A. Strong foliation
• B. No foliation
• C. Moderate foliation
• D. Weak foliation

Answer: (D)

Foliation forms when directed pressure aligns minerals into a planar fabric. Granulite facies rocks form at high temperatures where minerals recrystallize into equant grains, which tends to erase or prevent the development of a strong fabric. As a result, granulites usually show little to no foliation, often only a faint, weak foliation if any deformation fabrics are preserved. This is why weak foliation best describes granulite rocks, rather than strong or moderate foliation; and it’s more consistent than no foliation, since some faint fabric can occur with deformation, even if it isn’t well-developed.