Hidden Valley is a little known mine. The story is told in Turquoise in America Part Two 1910-1990 and Part Three The Stories of Turquoise 1990-2020.
 
This cab weighs 54.2 carats and measures 4cm X 3cm.It is priced at $75 a carat or $4065. It is not treated and backed. This is perhaps the rarest of all gem grade turquoise and priced below comparable grade. There is no way to find a price comparison because this is the only example available. I have assigned a TG of 94 or GG Gem Grade. This is a large cabochon, enhancing the rarity, and would make a stellar centerpiece in a masterpiece of Native American jewelry. This turquoise represents among the finest of all turquoise, destined for a fine collection.