Chalcedony
only in Re 21:19 The name is applied in modern mineralogy to one of the varieties of agate. It is generally translucent and exhibits a great variety of colors. So named because it was found near the ancient Chalcedon, near Constantinople.
Bibliography Information Smith, William, Dr "Definition for 'Chalcedony' Smiths Bible Dictionary". bible-history.com - Smiths; 1901.