New Never Worn 10mm White Agate Beaded Necklace 925 Sterling Silver Lobster Claw Clasp. White Agate is a form of Chalcedony, which is a mineral that is made up of microscopic crystals of Quartz. Agate is from the Latin word “achates,” the name of a river in Sicily where Agates were first discovered. White Agate has been used for various purposes throughout history, including as a protective amulet and for its healing properties.