Sunstone

Radiating with the power of eternal light, sunstone has been coveted since antiquity for its ability to guide its wearer through the journey of life. Sunstone is also known as aventurine feldspar or heliolite, from the Greek “helios” for sun and “lithos” for stone.

Legends and lore

An ancient gem, sunstone has allegedly been discovered in Viking burial mounds. It is thought that the Vikings actually used the light-polarizing properties of a stone to tell the direction of the sun on cloudy days. While this “sun stone” is thought to have actually been Iceland spar (calcite) or iolite, the name today is applied to a brilliant variety of feldspar.

Not only did the Vikings believe sunstone could aid navigation across the seas, but it was also considered a path-finding tool to Valhalla and the afterlife. Pope Clement VII (1478–1534) was reputed to have in his possession a sunstone with a golden spot that moved across the surface in accordance with the apparent motion of the sun from sunrise to sunset.

Native Americans in Oregon used sunstone for trade and barter. Oregon sunstone was declared the official gemstone of the State of Oregon in 1987. Sunstone is claimed by some sources to have been used by Tibetans in medicine rituals to help spirit guides access the healing power of the sun. When contact with the spirit guides was successful, the gem was said to glow a bright gold.

Crystal healers believe sunstone to be useful for adding personal insight and alleviating depression. Historically, sunstone has been linked with benevolent gods, luck and good fortune.

Just the facts

Sunstone is a member of the plagioclase feldspar group of minerals and occurs in the compositional range of oligoclase, labradorite and andesine. Orthoclase sunstones are also known.

The name feldspar comes from the German feldt spat, meaning field stone. So named, this is because when feldspar weathers, it releases large amounts of plant nutrients, such as potassium, which enrich soil.

Sunstone has a beautiful glittering sunlight effect as a result of its tiny metallic inclusions. The copper or hematite inclusions cause sparkling flashes of light as thousands of particles playfully interact with light, an effect known to gemologists as aventurescence. Many sunstones are cut as cabochons to display this phenomenon, but some may also be faceted to exhibit their superior luster.

Sunstone is formed and crystallized in lava flows, mica schists and pegmatites. The gem is typically mined with pick and shovel from the surface of partially decomposed rock or from shallow pits and shafts dug to retrieve the rough.

Sunstones range in color from water clear through pale yellow, soft pink and red to deep teal green. Some of the deeper colored gems have bands of varying color while others exhibit pleochroism, showing different colors when viewed in different directions.

The world’s most famous sunstone mines are in Oregon’s Harney and Lake counties, where a high copper content gives them their unique bright orange to red colors. Sunstone is also found in India, Canada, Tanzania, Tibet, Madagascar, Norway and Russia.

In 2002, a new supply of sunstone entered the market from an origin that is still subject to debate. Described variously as originating from the Congo and later from Tibet, testing proved the gems to be plagioclase feldspars in the labradorite/andesine compositional range. A swirling mix of coppery oranges, honeys, ambers, lemons and limes characterizes these sunstones, with a beautiful glittering sunlight effect caused by tiny copper inclusions.

While the copper and hematite inclusions in sunstone are predominantly orange or red, they sometimes disperse a fiery iridescence. This attractive blend of shimmering colors gives sunstone an appearance unlike any other gemstone. Fine sunstones are extremely rare and put this variety of feldspar in the same class as the best the gem kingdom has to offer.

Similar to alexandrite, the color change variety of chrysoberyl, in extremely rare specimens sunstone can also display the color change effect. In daylight it is green while in incandescent light it is a coppery red. Green and imperial (orange pink) sunstones are also available.

Tanzanian sunstone was first found by a young Masai man on tribal grazing lands near Arusha in 2000. This sunstone’s basic red-orange color mimics the bright hues of the Masai people’s dress. These gems have been marketed under various trade names, including illusion sunstone, tanzasun and Masai sunstone.

The Tanzanian sunstone features large flakes of vivid red and orange hematite, floating within a pale green to colorless feldspar matrix, with plates aligned parallel to cleavage planes. Local African miners call these large flakes flowers. In many cases, the hematite plates reflect a multitude of electric neon colors as the stones are rotated, creating a lovely kaleidoscope of color.

Cabochons with lots of hematite frequently display one or more cat’s-eye bands and weak stars are also found on occasion in some sunstones from Madagascar and Tanzania. This further accentuates sunstone’s natural sparkle.