Large vintage sterling silver pendant with an open back bezel that set with a natural turquoise stone. This piece is not Native American. Hallmark are on the bale see photo.  This stone has many attributes of the Kings Manassa Mine. The church brown matrix has ribbons of rust running through and is glittered with what must be tiny pyrite inclusions, but it looks almost like clear crystals. 

The stone measures almost 2" by 1 3/8". Pendant measures 2 1/2" long with the bail.