Turquoise is a rare and valuable stone in the colors of the turquoise spectrum Turquoise is a natural  phosphate grade of aluminum.This precious stone is found in Neyshabur. This Turquoise  Mine is one of the oldest turquoise mines in the world Which was extracted from turquoise stone from 2000 years ago and it is located in the northwest of Neyshabur. Turquoise of Neyshabur is the best-known and most expensive turquoise stone in the world.