In geometry, a polygon (/ˈpɒlɪɡɒn/) is a plane figure made up of line segments connected to form a closed polygonal chain.
https://github.com/davepinch/pinchy.cc/blob/master/content/topics/mathematics/shapes/polygon/wikipedia/en.wikipedia.org.md
Polygons appear in rock formations, most commonly as the flat facets of crystals, where the angles between the sides depend on the type of mineral from which the crystal is made.