mineralia

phantomquartz:

Rare “Pinapple” Opal

“Opal Pseudomorphs are created by the deposition of opal in casts (molds) of fossil bone, teeth, shell, belemnoids (ancient relatives of cuttlefish), crinoids (sea lillies), wood, fir cones and even skeletons of large prehistoric animals. Many of these fossilized forms contain exceptional quality noble opal. White Cliffs is the only place where these marvelous (and very rare) pseudomorphic “pineapple” opals have been found. They were formed when a mineral crystal of glauberite (or ikalite) was first replaced by calcite and then opalised.”

(via accio-peace)