Opalized fossil... Or unicorn horn...

Rare pictures from this crazy world.

All about the opal gemstone, its varieties, and its physical and metaphysical properties explained.

This ammonite is on display in our Elements gallery.

Opalized Fossils

Opalized Theropod. Dinosaur Tooth. Opalized fossils form when silica settles into cracks in the bone, then harden into opal. photo Carl Bento. Australian Museum.

Opal forms in cavities within rocks. If a cavity has formed because a bone, shell or pinecone was buried in the sand or clay that later beca...

Rare Opalised Wood From Nevada Nevada is famous for its beautiful, colorful black Opal. The state contains some very rich precious opal bed...