 | Controversy surrounding treated copper-bearing feldspar has hurt Oregon Sunstone mining. In the early 2000s, Asian treaters perfected a method of diffusing copper into pale feldspar, flooding the market with low-priced, attractive red and green gems—which destabilized the market for Oregon sunstone. Promoted as “andesine” and purportedly from mines in Congo or Tibet, this material was subsequently found to be treated, but the resulting furor hindered the public’s trust in natural copper-bearing feldspar. Despite this setback, Oregon sunstone miners have strived to rebuild the market, and there are signs of renewed consumer interest in their one-of-kind gems. |  |