What is a Trapiche Emerald?

This is a very rare type of emerald found only in Colombia from the mines of Muzo or Peñas Blancas.

It occurred when emeralds inter-grew with a different mineral like albite or carbonaceous shale trapped within them and formed a six axes wheel of black or gray-black color with the green among the axes. Trapiche emeralds are very rare configurations and are highly priced by collectors.

* Trapiche is the Spanish word for cogwheels in sugar mills