Image: Martin Lopez-Garcia, et al./Science...  ...that glitters is not gold ... sometimes, they're opal . Researchers at the University of Bristol...  ...e lattice structure that silicon dioxide takes in opals , to give the alga its special iridescent property...

Photo: Jeff Schultz/Flickr - via Bored Pan...  ...user Jeff Schultz took a photograph of a Mexican opal

Redditor Proteon posted this image of a fossilized...  ...posted this image of a fossilized snail turned to opal recently. Opal forms in cavities inside rocks. If a cavity is cr...  ...ter became the rock, and conditions are right for opal formation, then *strong class="mat...

(Photo: Opal Auctions)This beautiful fossil is a pine cone inf...  ...This beautiful fossil is a pine cone infused with opal . It was found in the Ken's Retreat opal mining area of Finch County, New South Wales, Aus...  ...s can be found here including--on rare occasions-- *s...

Photo: Carl Bento/Australian Museum...  ...'ve seen fossils in museums, but what about this: opalized dinosaur tooth. Opalized fossils occur when silica settled into cracks...  ...in the dinosaur bone and then hardened into opal . This one above is a particu...