Nonfoliated metamorphic rocks are more difficult to
identify because of their large, undeformed minerals.
Hornfels are nonfoliated rocks composed of
equal sized minerals in a random orientation. It is usually formed in
low pressure, high temperature, during contact metamorphism.
Quartzite is usually nonfoliated and
composed of recrystallized quartz. Sandstone and chert are the common
Marble is composed of either calcite or
dolomite, and usually derived from limestone. The purity of the marble
will depend on the purity of the limestone.
Serpentinite is nonfoliated, and composed
mainly of the mineral serpentine. Serpentinite also occurs as a fibrous
variety, especially found near fault zones.
Thin section of hornfel