Andalusite

Andalusite crystals in quartz vein. Andalusite is stable at low pressures and temperatures.

Apophyllite and Prehnite

The minerals in this metamorphic rock record the following temperature (T) and pressure (P) conditions within the Earth: T = 150-240°C, P = 500-1,750 atm.

Biotite

Biotite is one of the most common rock-forming minerals. By studying a rock's minerals, scientists uncover clues to its origins and history.

Chabazite and Analcime

The minerals in this metamorphic rock record the following temperature (T) and pressure (P) conditions within the Earth: T = 150-240°C, P = 500-1,750 atm.

Kyanite pseudomorph after andalusite

The blocklike shapes in the rock were once large andalusite crystals. Now they are occupied by hundreds of white blades of kyanite that formed when the rock was deeply buried and subjected to higher pressures. Kyanite is stable at high pressures and moderate to high temperatures.

Kyanite with quartz vein

The minerals in this metamorphic rock record the following temperature (T) and pressure (P) conditions within the Earth: T = 450-650°C, P = 4,000-7,000 atm.

Magnetite lodestone

Zap! Lightning created this lodestone--a natural, permanent magnet. Steel paper clips cling better to areas where the strongest current traveled. To make a lodestone, you need: an iron ore--in this case, magnetite; tiny, oriented inclusions of another iron mineral--in this case, maghemite; a bolt of lightning.

Muscovite

Muscovite is one of the most common rock-forming minerals. By studying a rock's minerals, scientists uncover clues to its origins and history.

Orthoclase

Orthoclase is one of the most common rock-forming minerals. By studying a rock's minerals, scientists uncover clues to its origins and history.

Plagioclase

Plagioclase is one of the most common rock-forming minerals. By studying a rock's minerals, scientists uncover clues to its origins and history.

Quartz

Quartz is one of the most common rock-forming minerals. By studying a rock's minerals, scientists uncover clues to its origins and history.

Stilbite and Chabazite

The minerals in this metamorphic rock record the following temperature (T) and pressure (P) conditions within the Earth: T = 175°C, P = 500-1,750 atm.

Zircon

Zircon, var. cyrtolite. Luster Group Pegmatite