Rock Elm: Home To One Of The Rarest Minerals In The World.

First discovered in a laboratory in the 1960’s, reidite has only been found in nature in five locations around the globe.


The Rock Elm Disturbance is an impact crater near the town of Rock Elm Wisconsin in Pierce County. Thought to be created during the Ordovician Period  of 450-430 million years ago, the Rock Elm Disturbance revealed a surprise to scientists when the rare mineral reidite was discovered at the site in 2014.

Reidite is a polymorph of zircon, one of the hardest minerals on Earth. It is formed with the same molecules as zircon, under high impact extreme pressures and temperatures, such as during a meteor impact. Reidite is 10 times denser than zircon. Reidite takes it’s name from Alan F. Reid, the scientist who discovered it in a laboratory in 1969.

The discovery was made by NASA Astrobiology Institute member Aaron Cavosie of the University of Puerto Rico with a team of students from the University Of Wisconsin while collecting samples at the meteor impact site. The Rock Elm reidite was only the fourth discovery of natural reidite. Prior to the Wisconsin discovery, reidite was only found in nature at the Chesapeake Bay Crater in Virginia, the Xiuyan Crater in China, and the Ries Crater in Germany. It has since been found at a fifth site in 2015, at the Stac Fada Member in Northern Scotland. Scientists believe the Scottish site is over one billion years old, predating the previously discovered sites including Rock Elm.

For more about this fascinating western Wisconsin discovery, check out this great article with videos of the Rock Elm site.


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