EGU Blogs

Geology Photo of the Week #47

This week’s photo is another mineralogy themed one. This photo shows beautiful, yet also flattened crystals of the mineral natrolite that has grown in an acicular habit from a central point making them look sort of like little snowflakes. Natrolite is a relatively common hydrated sodium, aluminum silicate mineral (Na2Al2Si3O10 · 2H2O) that often forms within the void spaces of igneous rocks such as amygdular basalt. In this instance it looks like natrolite has formed along a fracture plane due to its flattened appearance suggesting the only room it had to grow was outward as opposed to up, which is why it has made these “snowflake” shapes.

Crystals of natrolite along a vein in urtite (foidolite) by Dmitry Zhirov

Crystals of natrolite along a vein in urtite (foidolite) by Dmitry Zhirov

Matt Herod is a Ph.D Candidate in the Department of Earth Sciences at the University of Ottawa in Ontario, Canada. His research focuses on the geochemistry of iodine and the radioactive isotope iodine-129. His work involves characterizing the cycle and sources of 129I in the Canadian Arctic and applying this to long term radioactive waste disposal and the effect of Fukushima fallout. His project includes field work and lab work at the André E. Lalonde 3MV AMS Laboratory. Matt blogs about any topic in geology that interests him, and attempts to make these topics understandable to everyone. Tweets as @GeoHerod.


  1. There’s also some calcite in there, and the square outlines *may* be apophyllite, but I can’t see enough detail to be confident.

    • Good eye Lockwood!!

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