How is Chalcedony Used?

“Chalcedony is a form of chert, and perhaps the most widely used of all gems through the ages. In fact, apart from sticks, bones and plain rocks, chalcedonies may have been the earliest hard materials used by mankind, shaped into arrowheads, knives, tools, cups and bowls…It was a sacred stone for Native Americans, said to promote stability and harmony.” - John Farndon, The Illustrated Encyclopedia of Rocks, Minerals & Gemstones.