Fire-opal skull from Magdalena, Jalisco, Mexico

The mineraloid opal is an amorphous variety of quartz, SiO2 · nH2O, hydrated silicon dioxide with a water percentage of up to 20%. Opal can be colorless, white, milky blue, gray, red, yellow, green, brown and black. Often, many of these colors will be seen right away, caused by interference and diffraction of light passing by tiny, regularly arranged openings within the micro-structure of the opal, known as the Bragg grating. These openings are filled with secondary silica and form thin lamellae inside the opal during solidification. The term opalescence is used to describe this unique and beautiful phenomenon, although iridescence a better term would be. The opal is one of the minerals that are able to replace or fossils. The resulting fossils are saved by collectors. "Opal" is derived from the ancient Indian word Upala ", meaning gem. A distinction between the glistening edelopalen, the yellow and red vuuropalen ordinary opals. Their physical properties exhibit important differences. The opal is the official gemstone of South Australia. Opal has been used since ancient times treated as a gemstone. Initially it was used for the manufacture of primitive tools, and later for decorative objects. Opal has been used for the Assyrians, Babylonians and Romans. Edel Opal is one of the most mysterious stones. Traditionally it was considered a stone that brings misfortune, especially for people who are not properly cleansed the stone, the precious opal which Pliny described comes from the deposits of Dubník in Slovakia, which have been mined at that time. They wrote this stone to magical powers. He helped against melancholy, calmed the nerves, heal the heart, protected against worries, restored eyesight and gave the eyes shine again. In addition to naturally occurring opal, opal is produced in many different ways, experimental and commercial. The resulting material is to be distinguished from natural opal by its regularity; under magnification, the patches of color are seen in a "lizard skin" or "chicken wire" pattern are arranged. Synthetics are further distinguished from natural opal by the lack of the former to phosphorescence under UV light. In addition, synthetic opals are generally lower in density and are often highly porous; some may even stick to the tongue. Two notable producers of synthetic opal are the companies Kyocera and Inamori in Japan. The majority of so-called synthetic opals, however, be more correctly referred to as imitation, since they contain substances that are not found in natural opal (eg, plastic stabilizers). The Gilson opals often seen in vintage jewelery are actually imitation consisting of laminated glass with bits of foil interspersed.

The crystal skulls are from quartz or rock crystal faceted artwork in the shape of human skulls. This appeared in the second half of the nineteenth century and were originally assigned to various precolumbiaansebeschavingen. Research in the last decade of the twentieth century, among other things with the aid of a scanning tunneling microscope showed that in each case a number of these skulls are counterfeits. These are made with grinding tools which until the second half of the nineteenth century developed werden.Er is a strong presumption that produced some of the crystal skulls were commissioned by the French dealer Eugène Boban and sold by him. One of the most famous skulls is the Mitchell-Hedges skull. This would have been found by the British adventurer FA Mitchell-Hedges in a space under the ruins of Lubaantun in Belize. Later he appeared to have this skull bought privately in the London auction house Sotheby's. His wife gave as his reason that he gave the skull just as collateral to someone and it had repurchased through Sotheby's. After the death of Anna Mitchell-Hedges, the skull came into the possession of Bill Homann. In the nineties it became clear that the Mitchell-Hedges skull was a fake. In the meantime, the necessary hypes and legends formed around the crystal skulls. Their so-called site they'd centuries ago by the Mayans, the Aztecs or even 0udere precolumbiaansse civilization were manufactured. Would have these psychic abilities and would never right may look in the eyes. According to another legend, they would have an extraterrestrial origin. There would find thirteen of on earth. Once reunited, they would share their knowledge with humanity. Even now play the skulls still has a role in some of the New Age community.

In fiction:
• In the movie Indiana Jones and the Kingdom of the Crystal Skull from 2008 all the above legends are combined.
• The hidden crystal, a book by Manda Scott, is about the crystal skulls and the 2012 phenomenon of the Maya.
• In the 21st episode of season 3 of the science fiction series Stargate SG-1 2000 (Crystal Skull) Daniel Jackson disappears when he looks into a crystal skull.

• The Assassin's Creed series refers to the skulls, where the ancient artifacts with mysterious powers.

Gemstone skulls. Gemstone skulls are already popular and mysterious to many cultures since many decades. The skulls have a very different meaning. Celtic skulls symbolize Time, Strength, creation, initiation and concentration. Celtic culture believes the skull is a seat of power and strength. Some texts refer to the cranium as the seat of the soul. Archaeological findings tell us that the ancient Celts skulls sacrificed to holy wells. The skull is universally recognized as the symbol of life and death. More recently, the skull linked to death and embracing our mortality. In ancient times, the skull was sometimes for life. Skulls and skeletons are the symbol for the Mexican holiday, the day of death. The skull and crossbones is a popular symbol for pirates and poison. Some healers use skulls to see visions of the past, present and future. including rose quartz, rock crystal, rhodonite, aventurine and hematite.