Deformed Spinel Peridotite

Under mantle temperatures and pressures, solid rocks can flow like a glacier. The spinel peridotite contains bands of strongly sheared and deformed crystals.

Garnet Peridotite

Peridotite is the most abundant rock of the upper mantle. The tiny dark red garnet crystals are evidence that it formed deeper than 60 km (37 mi) below Earth's surface. Nearer the surface, garnet is transformed to spinel.

Garnet Peridotite

Peridotite is the most abundant rock of the upper mantle. The tiny dark red garnet crystals are evidence that it formed deeper than 60 km (37 mi) below Earth's surface.

Garnet Peridotite

Peridotite, the upper mantle's most abundant rock, is named for peridot -- the gem variety of olivine. Peridotites contain mineral clues to how deep the rocks were formed. The mineral garnet, present in this sample, is stable at depths greater than 60 km (37 mi).

Peridotite

Earth's mantle contains more water than all the world's oceans. Where is it? Locked up within the structures of minerals. The golden brown crystals in this peridotite are the mineral phlogopite, a Mg-rich mica that has four percent water (by weight).

Peridotite Xenoliths in Basalt

This lava is chock-full of green and dark reddish-brown peridotite xenoliths.

Peridotite Xenoliths in Basalt

This lava is chock-full of green peridotite xenoliths.

Spinel Peridotite

Peridotite, the upper mantle's most abundant rock, is named for peridot -- the gem variety of olivine. Peridotites contain mineral clues to how deep the rocks were formed. The mineral spinel, present in this sample, is stable at depths shallower than 60 km (37 mi).