Many claim that Rainbow Calsilica is a naturally occurring material discovered in the veins or seams of volcanic rhyolite in a mine in Chihuahua, Mexico, but there is little evidence to support this claim. Geologists are denied access to the mine to determine if the stone is in fact real or manufactured. Only photos of the mine have been released. the Swiss Gemological Institute purchased and analyzed Calsilica said to be from the mine in Mexico and found that the base white materials were indeed a calcite. However, they also found man-made coloring pigments within the specimens. More importantly, they found that the particles were bonded together by a transparent soft, plastic-like material that was very similar to paraffin wax. Natural or unnatural, Rainbow Calsilica continues to be a mysterious, controversial gemstone with unmatched color combinations and striking beauty.