What is fault breccia?

Angular broken rock fragments cemented together

How does mylonite form?

By ductile shearing and recrystallisation at greater depth

By shallow crushing of brittle rock

Differentiate between fault gouge, fault breccia and mylonite.

Point	Fault gouge	Fault breccia	Mylonite
Nature	Soft, clay-like, finely ground rock powder	Angular broken fragments of rock cemented together	Hard, fine grained, banded rock
Grain size	Very fine (clay to silt)	Coarse, angular fragments (>2 mm)	Very fine, crushed and recrystallised
Formation	Intense grinding at shallow depth along the fault	Crushing at shallow depth in brittle rock	Ductile shearing and recrystallisation at greater depth
Fabric	Unconsolidated, soft	Chaotic, no foliation	Foliated, banded
Strength	Very weak, plastic when wet	Weak to moderate	Fairly strong but brittle
Engineering	Impermeable but unstable; causes sliding and squeezing	Permeable; leakage and instability	Planar weakness along banding

✓ Answer checked by Claude Opus 5.5 (high effort)