Lava Gems: Finding Obsidian and Peridot in Volcanic Fields

For rockhounds and mineral collectors, volcanic fields are treasure troves that offer a unique opportunity to discover two stunning gems: obsidian and peridot. These minerals not only enchant with their beauty but also tell stories of geological processes that date back millions of years. This article will guide you through understanding these two volcanic gems, their properties, and how to locate them in nature.

Understanding Obsidian

Obsidian is a naturally occurring volcanic glass formed when lava cools rapidly. It has no crystalline structure, which gives it a glassy luster and smooth feel. The typical composition of obsidian includes silicon dioxide (SiO2) at approximately 70% or more. Many rockhounds are drawn to obsidian for its diverse colors and potential for unique patterns, which can be a result of varying mineral inclusions.

Properties of Obsidian

Color: Obsidian commonly appears in black but can also be found in shades of brown, green, and even rainbow hues, thanks to different mineral content.
Hardness: On the Mohs hardness scale, obsidian ranks between 5 and 6, making it a relatively fragile gem compared to other minerals.
Fracture: It exhibits a conchoidal fracture, meaning it breaks with a smooth, curved surface.

Locating Obsidian

To find obsidian, you should explore areas with recent volcanic activity or geological formations known for basaltic rock. Popular locations include:

Mount St. Helens, Washington
The San Gabriel Mountains, California
Newberry National Volcanic Monument, Oregon

When hunting for obsidian, look for shiny, black to brown chunks among rocky outcrops. It is advisable to use a metal detector, particularly in areas with a lot of gravel, as obsidian can be buried beneath the surface.

Understanding Peridot

Peridot is a gemstone-quality variety of the mineral olivine, which forms in igneous rocks at high temperatures. This gem ranges in color from light olive green to a rich lime green, largely due to the presence of iron. Peridot is one of the few gemstones that occur in only one color, although variations in hue can exist due to the iron content and the crystals formation conditions.

Properties of Peridot

Color: The most sought-after peridot displays a vibrant green hue, often compared to lime or even avocado.
Hardness: Peridot ranks at 6.5 to 7 on the Mohs scale, making it more durable than obsidian.
Crystal System: Peridot forms in the orthorhombic crystal system, resulting in distinctive crystal shapes.

Locating Peridot

Peridot is typically found in volcanic rocks, particularly in areas where the mantle has been exposed. Significant locations include:

Hawaii (especially the islands of Hawaii and Lanai)
The San Carlos Apache Indian Reservation, Arizona
Peridot Mesa, Arizona

To find peridot, examine areas with basaltic rock formations, particularly in regolith or weathered layers. Look for small olivine crystals, which might indicate that you are in the right area.

Practical Tips for Collectors

When searching for obsidian and peridot, consider the following practical tips to enhance your rockhounding experience:

Research geological maps to identify volcanic regions that fit your interests.
Carry essential tools such as geologists hammers, safety goggles, and sturdy gloves to protect your hands while working with rocks.
Engage with local rockhounding clubs or communities for guided trips and insider tips.
Always check local regulations regarding rock collection to avoid legal troubles and preserve natural sites.

Conclusion

Exploring volcanic fields for obsidian and peridot can be a rewarding experience for rockhounds and mineral collectors alike. With an understanding of their properties, locations, and practical tips for collecting, you are well-equipped to unearth these stunning gems. Embrace the adventure, and you may just find your own lava gems amidst the earths volcanic wonders!