Thunder Mountain is a producing mine in Esmeralda County Nevada. The story is told in Turquoise in America Part Three.
 
This cabochon weighs 16.6 carat and measures 3cm X 2cm X 4mm. The price is $80/ct or $1328. It is not treated and is backed. I have assigned a TG of 91 or GG. I purchased this stone from Shreve Saville. White spot is camera flash.