A pure copper crystal with dendritic structure, electrolytic made. Picture taken by a scanning electron microscope "ULTRA plus" (Zeiss) with an acceleration voltage of 3 kV and a magnification of x 2500.
<a href="//commons.wikimedia.org/wiki/User:Tzaph" title="User:Tzaph">Tzaph</a>
<span class="int-own-work" lang="en">Own work</span>