| Sunstone is official Oregon's state gemstone.
A gemstone sunstone is a transparent or translucent feldspar crystal with a wide variety of colors including clear white, yellow, red, green, and blue. The size of specimens is usually between an inch and two. Oregon sunstones, also called heliolite, are unique. They have cooper inclusions that provide a shimmering optical effect known as schiller or aventurescence. Light is reflected from the tiny copper platelets and when viewed from the certain angles exhibits a bright flash of light to the eye.
Color relates to the amount of copper in the sunstone. The red stone contains the highest concentration of copper, over 200 parts per million (0.02%). Green - 100 parts per million (0.01%). Yellow - 20 parts per million (0.002%). The highest copper concentration makes Oregon sunstones highly-prized.
Some crystals can exhibit colors changes, be showing pink on one side and red on the opposite side of the stone. Other sunstones might have green patches with the red color. The rare and most valuable stones have dichroic or trichroic properties that mean the colors or color depth are changed when observed from different directions. Also, some the rarest sunstones resemble alexandrite, change the colors in different light.
Sunstone value is defined by transparency, color, and the quality of aventurescence.
A calcium-rich Oregon sunstone formed in molten basaltic lava flows thirteen to fourteen million years during Steens Mountain eruption. For thousands of years, the lava remained under water. Weathering and drying out lakes led to the basalt flows were exposed and the sunstones crystals released.
Where to Find Sunstones
Sunstone has been found in many locations around the world including Canada, Mexico, Norway, Australia, Russia, China, Tanzania. and the United States of America including New York, Virginia, Pennsylvania, and Oregon.
Southeastern Oregon is the only area in the world where the gem graded sunstones with copper inclusions are found. There are three sunstone productive deposits in Oregon: one in the Lake County and two in the Harney County. Most locations are within the private mining claims. Collecting on mining claims without the owners' permission is prohibited.
Bureau of Land Management (BLM) established the Oregon Sunstone Public Collection Area in Lake County between the Warner Valley and Albert Rim.
Also, sunstones can be collected on commercial Spectrum Sunstone Mine and Double Eagle Mine, both are located near Plush.