Gem Profile- Sunstone

by Judy Ellis

Today's profile on Sunstone is the last in this series on Feldspar. Did you miss any of the Feldspars that we covered? Here they are again: Amazonite, Labradorite, Moonstone, Sunstone.

Sunstone Facts

Sunstone is a type of feldspar in the plagioclase series.

For years, quality sunstone specimens were rare, but large deposits in eastern Oregon, including gem-grade material, made it more commercially available. Oregon named sunstone its official state gemstone in 1987.

Sunstone is often confused with other plagioclase feldspars, such as labradorite and albite, due to similar specific gravity and composition.

These minerals form rock formations, and any rock with extremely smooth cleavage that resists scratching may contain sunstone or another plagioclase feldspar.

The largest and most stable sunstone crystals, found in granite veins in Norway, are typically combined with calcite, quartz, epidote, and orthoclase.

Sunstone likely gets its name from the bright flashes of light it produces or its color, which resembles the setting sun.

It is sometimes called aventurine feldspar because it can resemble aventurine and display a reflective effect known as aventurescence.

This type of sunstone is typically oligoclase, while other sunstone is orthoclase.

Oligoclase sunstone, also called heliolite meaning "sun stone" in Greek is sometimes referred to as confetti stone due to its mass of glittering hematite particles.

Confetti Sunstone, cut and polished, then wrapped with 22-gauge sterling silver square wire and accented with a CZ snapset, by Beba Adams

Oligoclase was named in 1826 by August Breithaupt, a German mineralogist and professor at Freiberg Mining Academy, who succeeded Friedrich Mohs of Mohs scale fame. The name comes from the Greek words oligos ("little") and clasei ("to break") because the mineral is extremely brittle and has less perfect cleavage than albite.

Oligoclase ranks 6 to 6.5 on the Mohs scale, has a specific gravity of 2.6, and forms tabular crystals of hematite and goethite. These crystals are often twinned, meaning they consist of two or more components reversed relative to one another but existing in the same plane.

These twinning patterns can result from sporadic magnetic reversals of the Earth's poles.

Faceted sunstone mined and cut by Bob Bleily, all from Oregon, USA. Private collection, Dale Armstrong.

Sunstone Sources and Appearance

Sunstone is primarily found in India, the United States, Canada, Norway, China, and Russia. Oligoclase, a type of sunstone, is usually clear or white and glass-like, but some gemstone-quality specimens show a slight bluish sheen. Translucent to pale blue oligoclase occurs in North Carolina and Tanzania, while crystals in weathered marble are found in St. Lawrence County, New York. Sunstone is also mined in Millard County, Utah.

Some oligoclase contains hematite (iron oxide) inclusions, which cause sunstone to brilliantly reflect sunlight. When cut as a cabochon, this effect produces a reddish, sparkling, sun-like appearance. Colorless and translucent sunstone, such as North Carolina oligoclase, is faceted as a gemstone and can sometimes be confused with moonstone when it appears white and luminescent.

Oregon Sunstone is unique for containing tiny copper flecks, producing stones that range from clear to red, pink, and even green. Some Oregon Sunstones can even change color under different lighting, similar to alexandrite.

A sunstone cabochon wrapped into a pendant by WS Faculty member Sherrie Lingerfelt.

Sunstone in Culture

Unlike moonstone, which in 11th-century Europe was believed to reunite lovers, sunstone is associated with wellness, physical energy, vigor, and valor.

The ancient Greeks thought sunstone could protect the Earth and keep the Sun on its proper course.

Sunstone was discovered in an 18th-century excavation of an Aztec calendar and is mentioned in medieval Icelandic texts as a tool to locate the Sun on overcast days, though this may refer to a generic "sun stone" rather than the specific gem.

Crystal healers use sunstone to clear chakras and promote wellness and peace of mind.

A common manmade imitation is goldstone, a glass gemstone simulant that mimics sunstone's glittery, aventurescent effect.

Sunstone wrapped with 21-gauge square sterling silver wire and Swarovski® accents by Deborah Hamilton

Resources

Print Resources:

Eyewitness Handbooks' Rocks and Minerals by Chris Pellant, ISBN 1-56458-033-4

Peterson Field Guide to Rocks and Minerals by Frederick H. Pough, ISBN-0-395-91096-X

Smithsonian Rock and Gem by Ronald Louis Bonewitz, ISBN 0-7566-0962-3

Internet Resources:

www.mindat.org
www.wikipedia.org

Gem Profile- Sunstone

Materials

Tools

Reviews

Other Articles by Judy Ellis

Supplies

Resources

About Us

Connect With Us