Halite, Rock salt, Sodium chloride, NaCl; Collection of the Institute of Mineralogy,  University Tübingen. Used in homeopathy as remedy: Natrium chloratum / Natrium muriaticum (Nat-m.)
<a href="//commons.wikimedia.org/wiki/User:Llez" title="User:Llez">H. Zell</a>
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<span class="int-own-work" lang="en">Own work</span>