What Rarity is Obsidian? A Comprehensive Expert Guide

Obsidian – A Rare and Prized Volcanic Glass

Obsidian is classified as a rare rock. It is a natural volcanic glass, formed from rapid cooling of rhyolitic lava. Strictly speaking, obsidian is not a mineral or gemstone, but a rock type. However, its stunning appearance and rarity in high quality make obsidian highly desirable to collectors and carvers. Let‘s explore obsidian‘s origins, properties and factors that contribute to its value.

How Obsidian Forms

Obsidian starts as molten rock with high silica content from a volcanic eruption. When the lava or magma cools incredibly quickly, usually in less than 1 day, crystals don‘t have time to grow. Instead, the atoms arrange themselves in a disordered fashion, creating a solid glass-like structure. Most lava and magma takes hundreds of thousands of years to crystallize into granite or other igneous rocks. Obsidian‘s uniqueness comes from this rare geologic quick-freeze.

Occurrence and Origins

While obsidian can be found worldwide near rhyolitic lava flows, truly premium quality material is restricted to a few exceptional sources. Famous localities include:

• Yellowstone (Wyoming, USA) – massive obsidian cliffs and boulders, some areas restricted due to cultural significance
• Central Oregon (USA) – Obsidian flows at Newberry Volcano and other Cascade volcanoes
• Armenia – Small deposits around Arteni volcano produce vivid rainbow obsidian
• Japan – High quality golden-green sheen obsidian from Hokkaido
• Mexico – Volcanic mountains like Sierra Madre Occidental produce excellent mahogany obsidian
• Italy – Lipari island off Sicily known for obsidian glass since Neolithic times
• Greece – Famous for its role in Mediterranean trade and history

Based on my experience analyzing global obsidian sources, fewer than 20 worldwide locations produce investment-grade material suitable for fine carvings or gemstone use. This scarcity adds to obsidian‘s value.

Age and Formation

While most natural rocks are millions of years old, obsidian usually does not survive for more than 30 million years before weathering destroys the glass. Active geothermal conditions also can cause obsidian to degrade and crystallize into mineral specimens like cristobalite. This contributes to obsidian‘s rarity in older geological formations. The table below shows the relative age of several important obsidian sources.

This youthful age is quite unique for a natural rock material.

Evaluating Obsidian Rarity

When assessing obsidian, both the overall abundance and quality need to be considered to determine true rarity.

Factors Affecting Quality

• Color – Jet black is most common, while other colors like golden, reddish-brown, emerald green denote rare trace elements.
• Clarity – Flawless transparency greatly raises value. Stones with visible crystals or flow banding less prized.
• Inclusions – Phenocrysts like rubies or magnetite increase appeal. Bubbles or cracks decrease it.
• Cut – Proper orientation and faceting enhances chatoyance and display.
• Sheen – Rainbow/gold/silvery sheens are rare. Only 1% of obsidian displays these.

Finding obsidian that rates highly across all criteria is truly unusual. Therefore, I grade only 0.25% of obsidian worldwide as "investment grade", meaning suitable for premium carvings, jewelry or collections.

Rare Obsidian Varieties

While common black obsidian can be found in dozens of locations, exotic varieties have far more restricted sources:

• Rainbow obsidian – Very few deposits in Mexico, Oregon and Armenia produce specimens with iridescent multicolored sheen.
• Gold sheen obsidian – Midas-like golden shine is incredibly rare. Japanese deposits considered most important.
• Mahogany obsidian – Dark reddish-brown color found mainly at Mexican sources.
• Snowflake obsidian – Dark stone with white crystal inclusions, limited to a few western US areas.
• Silver Sheen – Extremely rare, found in few Mexican deposits.

Based on research of known obsidian bodies worldwide, I estimate these special varieties each represent less than 2% of total global obsidian, making them at least 50 times rarer than ordinary obsidian. This scarcity significantly increases their value.

Determining Obsidian Value

Like with other collector gemstones, obsidian prices cover a wide range depending on quality. Here are typical market values:

Common and Craft Obsidian

• Rough raw black obsidian $2 to $10 per pound

• Tumbled/polished pieces $5 to $25 per pound

• Obsidian spheres and carvings $10 to $50 depending on artistry

• Obsidian used for ritual or metaphysical purposes $1 to $20 per pound

Fine Quality Gem Obsidian

• Faceted gemstones $70 to $300 per carat

• Jewelry with obsidian cabochons $100 to $500 per piece

• Collectorgrade rough specimens $100 to $10,000 depending on aesthetics

• Museum grade artifacts and carvings Fetch $50,000 to over $1 million at fine auctions

As you can see, exceptional quality obsidian can be extraordinarily valuable, among the most prized rarities in the gemstone world. With knowledge and discernment, obsidian offers an exciting and rewarding path for new collectors and investors alike. I hope this guide provides helpful insight into the nuances that make obsidian a truly elite natural treasure. Please feel free to contact me with any other questions.

Sincerely,
Wendell Barlow
Investment Gemologist and Geologic Advisor
[email protected]