Imaggeo on Mondays: A mineral under the microscope

Epidote by Gunnar Ries, distributed by EGU under a Creative Commons license

Epidote, an abundant rock-forming mineral found in metamorphic rocks, nearly always appears in green, although it may vary in shade and tone. Under a microscope of polarized light, however, it exhibits strong pleochroism, that is, it shows different colors when observed at different angles. The thin section (a laboratory preparation of a mineral or rock sample for use with a polarizing microscope) in the picture displays strong yellow colours, beautiful tones of pink and purple, and light and dark shades of blue.

This photography under a microscope was taken by mineralogist Gunnar Ries. He comments, “I took this picture in 1996 from a unakite sampled in the German state of Mecklenburg-Vorpommern, near the town of Rerik, during a field trip. The thin section was one of the first I ever made!”

Although Epidote can be found worldwide, including in Pakistan, China, and across Africa, it is particularly prevalent in the Austrian Alps, where it appears in the form of distinctly large, sharp, and lustrous crystals. Epitode is often seen on display at mineral conventions, with the finest pieces – featuring delicate and elongated crystals – being highly treasured by collectors.

Imaggeo is the online open access geosciences image repository of the European Geosciences Union. Every geoscientist who is an amateur photographer (but also other people) can submit their images to this repository. Being open access, it can be used by scientists for their presentations or publications as well as by the press. If you submit your images to imaggeo, you retain full rights of use, since they are licenced and distributed by EGU under a Creative Commons licence.

Bárbara Ferreira was the Media and Communications Manager of the European Geosciences Union from 2011 to 2019. Bárbara has also worked as a science writer specialising in astrophysics and space sciences, producing articles for the European Space Agency and others on a freelance basis. She has a PhD in astrophysics from the University of Cambridge.

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