Rutile quartz (quartz with enclosed <a href="https://en.wikipedia.org/wiki/Rutile" class="extiw" title="w:Rutile">Rutile</a> needles).
<a href="//commons.wikimedia.org/wiki/User:LivingShadow" title="User:LivingShadow">Simon A. Eugster</a>
CC BY-SA 3.0
<span class="int-own-work" lang="en">Own work</span>