Big Muscovite crystals in a Gneiss. Crossed nicols image, magnification 2x (Field of view = 7mm)
<a href="//commons.wikimedia.org/wiki/User:Strekeisen" title="User:Strekeisen">Strekeisen</a>
CC BY-SA 4.0
<span class="int-own-work" lang="en">Own work</span>