About Rainbow Cal Silica:

This is a fairly controversial stone that is only found in Chihuahua, Mexico.  It is composed of calcite allophane clay and is stabilized with resin in the same manner as most Turquoise.  The source mine  of this stone is kept secret by its discoverer.  The controversy is due in part to the secrecy of the source and also due to the fact that it is a strange formation to have occurred naturally. Some samples of the material sent to be tested have been reported to be man made while other samples have shown it to be a natural formation.  The conflicting tests only reinforce the mystery surrounding this very lovely, yet strange, stone.