Chalcedony 925 Sterling Silver Ring

Chalcedony (/kælˈsɛdəni, ˈkælsədoʊni/) is a cryptocrystalline form of silica, composed of very fine intergrowths of quartz and moganite. These are both silica minerals, but they differ in that quartz has a trigonal crystal structure, while moganite is monoclinic.