This is a lovely Gray Agate Sphere that was mined in Brazil.  It has extraordinarily beautiful patterns created with white and blue-gray brush strokes.  This is an excellent quality sphere!  Agate is a member of the quartz family and, specifically, a form of Chalcedony.  Native American Indians used the different forms of Chalcedony as a Sacred Stone because of its stabilizing and balancing effect on the body, mind, emotions, and spirit.