About Rainbow Calsilica :-Rainbow Calsilica (or Calsilica) is an opaque gem with colorful stripes/layers of light and dark blue, green, yellow, orange, red, black and occasionally even pink. Calsilica is a popular gem and is readily available as cabochons and carvings. It has been claimed that Calsilica is a natural form of microcrystalline Calcite with layers of various natural clay minerals as the bonding and coloring agents. It is claimed to be mined in Chihuahua, Mexico were it was allegedly discovered in the veins or seams of volcanic rhyolite in the mine. Although suppliers claim that Rainbow Calsilica is a natural stone, tests have indicated that it is powdered carbonate rock artificially colored and then stabilized with plastic. It contains a mixture of Calcite, silica, plastic and artifical coloring pigments such as PB15, an art-supply pigment, and a paraffin-like material. [ref: Winter 2002, Gems and Gemology, journal of the Gemological Institute of America].