Cryolite    Francon Quarry, Montreal, Quebec, Canada.  Ex. Dr. Steve Chamberlain collection.  Don Doell collector, 1978.  A fine example of this rare material in a large octahedral crystal with others (highly etched others) on a matrix of what appears to be calcite and possibly magnetite.  Main crystal is 1 cm on edge and the entire piece is 3.5 x 2.5 x 3 cm.  No damage but the crystal is not fully formed.  Exceptional example for Francon!  $100