Beautiful faceted and rough sapphire from the new Rock Creek sapphire mine. Photo by Andrew Lucas/GIA.

Rock Creek Montana Sapphires: A New Age of Mining Begins

Potentate Mining was recently featured on the website of the Gemological Institute of America (GIA), in an article by Tao Hsu, Andrew Lucas, Shane McClure, Nathan Renfro, and Kevin Schumacher. The richness of Rock Creek along with its history and geology are highlighted, as well as Potentate’s operation and responsible sourcing. Visit the link below for the GIA website, where a video and several galleries are available.


Of all the sapphire deposits found in Montana, the richest is in the Rock Creek (Gem Mountain) district. Between 1890 and the 1930s, over 65 tonnes of rough sapphire were recovered from this area and continuously supplied Switzerland’s watchmaking industry until the introduction of synthetic sapphire in the late 1930s.

For the first time in the past 120 years, the rich sapphire-bearing land in this area is owned by a single entity. To witness the beginning of a new era of sapphire mining in Montana and gain a full understanding of this operation, a GIA team visited the new Rock Creek sapphire mine in early August.


Sapphire was originally discovered in the Rock Creek area during gold exploration in the late 1800s, like many Montana sapphire deposits—gold mining was extremely popular in the area at the time. Since the climax of sapphire mining, boosted by demand from the watchmaking industry, local sapphire mining has largely supported the sapphire-oriented jewelry businesses in Philipsburg and the fee-paying sapphire hunters.

In 2011 the current mine owner, Potentate Mining, purchased the Eureka Gulch property on the north side of Gem Mountain and in 2014 finished purchasing the land on the south side. Today the company owns about 3,000 acres of sapphire-producing land in this historically important mining area.”