The crystal skulls were a hoax. The ones that were test were found to be made in the 19th century.
The crystal skulls are a number of human skull models fashioned from blocks of clear or milky quartz crystal rock, claimed to be pre-Columbian Mesoamerican artifacts by their alleged finders. However, none of the specimens made available for scientific study were authenticated as pre-Columbian in origin. The results of these studies demonstrated that those examined were manufactured in the mid-19th century or later, almost certainly in Europe.[1] Despite some claims presented in an assortment of popularising literature, legends of crystal skulls with mystical powers do not figure in genuine Mesoamerican or other Native American mythologies and spiritual accounts.[