Bisbee turquoise is one of the most famous of all turquoise. It is a byproduct from the Phelps Dodge Lavender Pit copper mine in Bisbee Arizona. The story of Bisbee is found in Turquoise in America Part Two, 1910-1990.
 
This cabochon weighs 29.6 carat and measures 2.50cm X 2cm X 4mm. It is priced at $15/ct or $444. It is not treated and is backed. I have assigned a TG of 76  or HMG.