Guess the name of the quarry from which the granite came? (www.usatoday.com)

Interesting fact in the last paragraph of this story, that I had never heard before:

Quote:  The gray granite for the monument came from the Pyramid Quarry just outside Elberton and now under new ownership. The site for the Guidestones was selected on a high ridge along Georgia Highway 77, seven miles from Elberton and eight miles from Hartwell.