The Dynamic Earth @ National Museum of Natural History

Actinolite-talc Schist

The container (right) shows how much water this rock contains. It formed deep in a subduction zone when the altered oceanic lithosphere began to release water.

Almandine-bearing schist

The minerals in this metamorphic rock record the following temperature (T) and pressure (P) conditions within the Earth:T = 500°C, P = 7,000-8,000 atm.

Garnet-muscovite schist

The minerals in this metamorphic rock record the following temperature (T) and pressure (P) conditions within the Earth: T = 550-650°C, P = 5,000-7,000 atm.

Gedrite-garnet schist

The minerals in this metamorphic rock record the following temperature (T) and pressure (P) conditions within the Earth: T = 650°C, P = 5,000-7,000 atm.

Kyanite-bearing schist

Blue kyanite crystals in a matrix of fine-grained mica. Kyanite is stable at high pressures and moderate to high temperatures.

Kyanite-bearing schist

Kyanite is stable at high pressures and moderate to high temperatures.

Schist

Bedrock under this museum, 530 million years old. During the continental collisions that built the Appalachian Mountains, heat and pressure transformed a sedimentary rock into this folded metamorphic rock.

Schist with rolled garnets

The red thumbprints in this rock are garnets that grew when the rock was glowing hot, 16 km (10 mi) below Earth's surface. The garnets took about 12 million years to get this big. In the process they rolled slowly like snowballs! The peculiar S-shaped patterns within the garnets are made of minerals trapped as the garnets grew. 400 million years old

Sillimanite-bearing schist

Sillimanite is stable at a wide range of pressures and high temperatures.

Staurolite-bearing schist

The minerals in this metamorphic rock record the following temperature (T) and pressure (P) conditions within the Earth: T = 500-550°C, P = 6,000-7,000 atm.