<p>Rock salt (halitite) (8.3 cm across) - blue &amp; whitish &amp; clear &amp; orangish rock salt (8.3 cm across) from the subsurface Salado Formation of New Mexico.  The orangish and bluish coloration is caused by radiation from potassium-40 in nearby potash salts, resulting in excess free sodium metal in the halite.
</p><p>Stratigraphy: McNutt Member (McNutt Potash Member), middle Salado Formation, Ochoan Stage, upper Upper Permian.
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Locality: Mississippi Potash East Mine, Carlsbad Potash District, Eddy County, southeastern New Mexico, USA.
<a rel="nofollow" class="external text" href="https://www.flickr.com/people/47445767@N05">James St. John</a>
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<a rel="nofollow" class="external text" href="https://www.flickr.com/photos/jsjgeology/8514005350/">Rock salt (Halitite), McNutt Member, middle Salado Formation, Ochoan Stage, upper Upper Permian; Mississippi Potash East Mine, New Mexico, USA</a>