Geological & Scientific Properties | Oregon Sunstone
Oregon Sunstone is a unique variety of the mineral labradorite, which is a member of the feldspar family. It is particularly notable for its distinctive coloration and optical phenomena. Here's an overview of Oregon Sunstone's geological and scientific properties:
Chemical Composition and Structure:
- Composition: Oregon Sunstone is composed of calcium sodium aluminum silicate. It often contains copper inclusions, which give it a distinctive glittering effect known as schiller.
- Crystal System: It crystallizes in the triclinic system, forming prismatic crystals.
Physical Properties:
- Color: Oregon Sunstone ranges in color from water-clear through pale yellow, soft pink, and blood red to deep blue and green. The presence of copper imparts a red to greenish or blue coloration and is responsible for the schiller effect.
- Hardness: It has a Mohs hardness of about 6 to 6.5, making it suitable for jewelry, but care must be taken as it can cleave.
- Luster: The luster is typically vitreous.
- Transparency: This gemstone can range from transparent to translucent.
Optical Properties:
- Refractive Index: The refractive index of Oregon Sunstone ranges from about 1.560 to 1.572.
- Pleochroism: It exhibits pleochroism, meaning it can show different colors or depths of color when viewed from different angles.
Geological Occurrence:
- Formation: Oregon Sunstone is found in basalt flows in certain parts of Oregon, USA. It is believed to be formed from cooling basaltic lava flows.
- Associated Minerals: It may be found associated with other volcanic rock minerals.
Major Deposits:
- The most significant deposits of Oregon Sunstone are found in southeastern Oregon, particularly in the regions near Plush and Rabbit Basin. These are the only locations where this gemstone is mined, making it a relatively rare and prized variety.
Oregon Sunstone is highly valued not only for its beauty but also for its unique origin. It is popular in jewelry making and is the official state gemstone of Oregon. The copper inclusions that give it the characteristic schiller effect can create a range of appearances under different lighting conditions, adding to its appeal. Its rarity and distinctive properties make it a favorite among gemstone collectors and enthusiasts.
