Oregon sunstone has been made the official State Gemstone by proclamation of Governor Neil Goldschmidt and by a Joint Resolution of the Oregon Legislative Assembly. Oregon sunstones, a rare gem variety of the feldspar mineral group, occur in Lake and Harney Counties where they are dug from the soil and the underlying lava flows. Oregon sunstones are uncommon in their composition, clarity, and range of colors and occur in sufficient abundance to permit sustained production of faceted gems.
Sunstone crystals as large as 3 inches across have been found. In color, the gems range from water clear through pale yellow, soft pink, and blood red to deep blue and green. Some of the deeper colored stones have bands of varying color. A few of the sunstone crystals show two different colors when viewed from different directions. Other sunstones appear to be perfectly transparent, but when they are observed from just the right direction, a pink to red metallic shimmer flashes from within the stone, as if from a collection of small spots or from a mirror surface. These color variations and the shimmer (often called "schiller") are caused by tiny crystals of copper metal contained in varying amounts and sizes within the stones. The darker stones contain larger amounts of copper.
For many years, collectors have prized sunstones from eastern Lake County, near Plush, Oregon, where the U.S. Bureau of Land Management has established a free, public collecting area. Until recently, this was the only known occurrence. Two more occurrences in northern and southeastern Harney County have been discovered recently, allowing the mining of more marketable gems, and the geology of the area is favorable for the discovery of more deposits. Except for the BLM public collecting areas, all these producing areas are held by mining claims and are not available for collecting without permission of the claim owners.