Calcite crystals from the personal author's collection
<a href="//commons.wikimedia.org/w/index.php?title=User:Anatoly_Vlasov&amp;action=edit&amp;redlink=1" class="new" title="User:Anatoly Vlasov (page does not exist)">Anatoly Vlasov</a>
CC BY-SA 3.0
<span class="int-own-work" lang="en">Own work</span>