The Oregon sunstone was designated the state's official gemstone in 1987. Oregon sunstones (also known as heliolite) are uncommon in their composition, clarity, and range of colors. Collectors and miners attracted by them have been a boon to tourism and economic development in Oregon.

Oregon sunstones are a calcium-rich variety of transparent to translucent crystal feldspar ranging in color from water-clear to pale yellow, soft pink, blood red, and (extremely rare) deep blue and green. Some stones show two different colors when viewed from different directions.

The color of a sunstone is determined by the quantity of copper metal within the stone. These flat crystals of metal also produce unusual optical effects. Sunstones are mined from the soil and partially decomposed rock formed by weathering of the basaltic lava flows of south-central Oregon.

Source:

Oregon Sunstones: OR Dept. of Geology & Mineral Industries
State Symbols: Oregon Blue Book
GemArtGallery.com: Photos courtesy of Martin Guptill

Links:

Geological Symbols - 50 States List