Sunstone

Sunstone properties at a glance

Geology & background

Sunstone is a feldspar variety, usually oligoclase or labradorite, that forms in igneous rocks and shows a glittering optical effect from tiny mineral platelets within the crystal.

Sunstone has been used as an ornamental gem for centuries, valued in Scandinavia and elsewhere, and copper-bearing Oregon sunstone brought renewed attention to the gem in modern times.

How to identify Sunstone

• Look for a glittering metallic shimmer, called aventurescence, that flashes as the stone is tilted.
• Feldspar cleavage in two directions and hardness near 6 to 6.5 help confirm the identification.
• Tiny copper or hematite platelets create the sparkle, so distinguish it from simple orange feldspar.

Where Sunstone is found

Sunstone occurs as a gem feldspar in igneous rocks, with notable localities in the United States, India, Norway, Russia, Tanzania, and Canada.

How much is Sunstone worth?

Value depends on strength of aventurescence, body color, transparency, cut quality, and locality.

Common uses

• Faceted gemstones
• Cabochons and beads
• Jewelry
• Collector specimens

Interesting facts

• The sparkle of sunstone, called aventurescence or schiller, comes from light bouncing off countless tiny inclusions.
• Oregon sunstone is colored by copper and is the official state gemstone of Oregon.
• Sunstone can be either plagioclase or potassium feldspar depending on the deposit.
• Norway and Russia produced classic hematite-bearing sunstone long before the Oregon deposits became well known.

Care & safety

Sunstone is moderately hard but has feldspar cleavage, so it can chip or split on sharp impact.

Avoid inhaling dust. Do not cut, grind, or polish unknown specimens without eye protection and a proper respirator.

Related rocks & minerals

Quartz Quartz Family Labradorite Minerals Basalt Igneous Rocks Jadeite Silicate Minerals Kaolinite Silicate Minerals Lazurite Silicate Minerals