Corundum

This 64.14 carat sapphire crystal was recovered in July 2018 from the famed Rock Creek deposit located in the Sapphire Mountains near historic Philipsburg, Montana. More popularly known as Gem Mountain, gold miners discovered sapphires here in the late 1890s. Over a period of 110 years, several hundred million carats of gem-quality sapphire were produced from this site that noted gemologists and journalists describe as the “Rainbow Over Montana.” The crystal, believed to be the largest gem quality sapphire crystal unearthed in the US to date, is so pristine and undamaged that Potentate Mining decided to keep the crystal intact to be enjoyed by the public and named it the Ponderosa Sapphire. The sapphire shows a yellow core common to Rock Creek sapphires with a beautiful greenish-blue body color. It is the largest sapphire crystal from Montana in the National Mineral Collection.