This is a magnification of glass. The smooth and edge forms are due to slow or fast transitions of temperature of silicon. The colors are due to inclusions which cause light to be absorbed into the silicon. The bubbles are trapped air pocket that were caught during the transition during annealing.
<a href="//commons.wikimedia.org/w/index.php?title=User:Jpavlish&amp;action=edit&amp;redlink=1" class="new" title="User:Jpavlish (page does not exist)">John Pavlish</a>
<span class="int-own-work" lang="en">Own work</span>