Opal

Absolutely stunning example of Boulder Opal, with exquisite and colorful patterns.  It displays all colors of the spectrum, which unlike many other opals, cascade across the face in separate sections.  The opal filling is quite widespread and abundant with great balance and symmetry, uncommon except in the best specimens.
 
From Queensland, Australia.  Included with purchase is a small adjustable stand.  Please contact us with any questions.
 
Opal is a hydrated amorphous form of silica, prized by mineral collectors for its vibrant play of colors. It is technically not a mineral, but a mineraloid, because it does not have crystalline structure.  This gemstone forms in low temperatures within cracks of rocks, especially in sedimentary formations. Its iridescence comes from the diffraction of light within its internal silica spheres, creating a spectrum of colors that range from blues and greens to reds and yellows.
 
Varieties include common opal (without play-of-color) and precious opal (with the signature iridescence). Australia is a major source, although it can also be found in other locations like Mexico and Ethiopia. Opal has a Mohs hardness of 5.5 to 6.5, making it relatively soft and fragile.  Opal is so prized and popular that some sellers deal exclusively with opals, and you can find opal only dealers at most rock shows.