arizona, petrology

A journey to the center of the Earth | Peridotite xenoliths

You don’t need to go on a Jules Verne journey down to the center of the Earth, sometimes the center of the Earth is brought up to us! These rocks are examples of peridotite xenoliths. A xenolith is a fragment of rock that becomes enveloped by magma without being melted or incorporated into it. In these… Continue reading A journey to the center of the Earth | Peridotite xenoliths

petrology, sedimentary

Geo Lingo | The Language of Geologists

Does it ever feel like geologists are speaking a different language? With so many different terms to describe and categorize rocks, learning the lexicon of a geologist can be a bit daunting. To help learn some basic geo lingo, here’s a (far from comprehensive) guide of some of the most important classification and terms geologists… Continue reading Geo Lingo | The Language of Geologists


Rocks of Art

Under the cross-polar light from an optical microscope, this thin section of a rock almost looks like it could be stained glass. The grains of olivine and pyroxene in this peridotite sample display vibrant birefringence interference colors. Not all minerals have such vivid hues under a microscope, though. A mineral’s birefringence depends on its refractive… Continue reading Rocks of Art

petrology, tectonics


Besides its aesthetic beauty and awesome vibrant colors, eclogite is a very rare and important rock. Eclogites are mafic metamorphic rocks that are formed in subduction zone settings. They experience metamorphism at extremely high pressures (1.2 GPa), greater than those typical of the Earth’s crust, as well as medium to high temperatures. They are responsible… Continue reading Eclogite