Glass Buttes in central Oregon is the state’s premier obsidian collecting destination, offering miles of exposed volcanic glass in varieties you won’t find anywhere else. The site sits on public BLM land about 80 miles west of Burns, just south of U.S. Highway 20, and collecting is free for personal use with no permit required.
Glass Buttes: Oregon’s Top Obsidian Site
Glass Buttes is a massive volcanic complex roughly 20 kilometers long and 10 kilometers wide, stretching southeast across the high desert in the northeast corner of Lake County. The entire area is rich with obsidian, and you can find pieces ranging from small flakes to football-sized chunks scattered across the surface and eroding out of hillsides.
What makes Glass Buttes exceptional is the variety. The area is famous for mahogany obsidian, which has dark reddish-brown streaks that resemble wood grain. But collectors also find rainbow obsidian (displaying iridescent bands of color when held to the light), fire obsidian, gold sheen, silver sheen, and snowflake obsidian, all within the same volcanic complex. Different varieties tend to concentrate in different zones across the buttes, so exploring multiple areas pays off.
To reach Glass Buttes, drive U.S. Highway 20 between Bend and Burns. A signed turnoff leads south toward the buttes on unpaved roads. Mahogany obsidian is the easiest to find, with pieces visible along the roadsides at lower elevations. The more prized rainbow and red obsidian tend to be found higher up, closer to the butte tops. Some collectors report that simply walking the dirt roads turns up good specimens without any digging at all.
Obsidian Varieties and What to Look For
Not all obsidian looks the same, and knowing what you’re after helps you spot it in the field. Standard black obsidian is volcanic glass in its purest form, solid and glossy. Mahogany obsidian contains iron inclusions that create those signature dark streaks. Both are common at Glass Buttes and easy to identify.
Rainbow obsidian is the collector favorite. It looks like ordinary black glass until you angle it in sunlight, when thin layers of tiny mineral crystals produce bands of green, purple, and gold. Fire obsidian is similar but rarer, with bright flashes of color from even thinner layers. Gold sheen and silver sheen varieties display a metallic glow across the surface. Snowflake obsidian has white, flower-like crystal clusters (called spherulites) embedded in the black glass. All of these form through slightly different cooling conditions in the same volcanic system, which is why Glass Buttes produces such diversity in a relatively small area.
Other Collection Sites in the Region
While Glass Buttes gets the most attention, obsidian occurs across Oregon’s volcanic landscape. The Newberry Volcanic Monument south of Bend contains significant obsidian flows, though collecting restrictions apply within the monument. Always check current regulations before collecting in any national monument or wilderness area.
Just across the state line, the Warner Mountains in northeastern California’s Modoc National Forest offer designated obsidian collection areas on a seasonal basis, typically open from July 1 through September 1. If you’re already making the drive to central Oregon’s high desert, the Warner Mountains are a reasonable side trip and produce quality black obsidian. The U.S. Forest Service manages these sites and posts seasonal updates each year.
Collection Rules on BLM Land
Glass Buttes sits on Bureau of Land Management land, where casual rock collecting for personal use is allowed without a fee or permit. The BLM defines a reasonable daily collection amount as under 250 pounds. If you want to collect more than that in a single day, you’ll need a BLM permit and may need to pay a fee or submit a plan of operations.
A few important rules apply. Collection must be for personal use, not commercial resale. You cannot use explosives or heavy mechanized equipment. Hand tools like rock hammers, chisels, and pry bars are fine. You also cannot collect from archaeological sites. Glass Buttes has documented archaeological sites where Indigenous peoples quarried obsidian for thousands of years, including a major site near the buttes proper that spans about 1.5 kilometers north to south. These areas are protected, and removing artifacts (worked points, flakes from tool-making) is a federal offense. Stick to collecting natural, unworked obsidian.
What to Bring
Obsidian is volcanic glass, and freshly broken edges can be sharper than surgical scalpels. Thick leather gloves are essential, not optional. Even experienced collectors cut themselves handling raw obsidian. Wear sturdy boots and long pants, since sharp fragments litter the ground in productive areas.
For tools, a rock hammer and a few cold chisels let you free specimens from matrix rock. A pry bar helps with larger pieces. Bring plenty of newspaper or old towels to wrap specimens so they don’t chip each other on the drive home. Five-gallon buckets work well for transport.
Glass Buttes is remote high desert with no services, cell coverage, or water. Bring more water than you think you need, food, a full tank of gas, and a spare tire. The access roads are unpaved and can become impassable when wet. Summer and early fall offer the best conditions, though the area can be extremely hot in July and August. Spring visits are possible but check road conditions first, as snowmelt can turn the roads to mud.
Identifying Quality Specimens
The best obsidian specimens are free of fractures and have a consistent, glassy luster. Hold pieces up to sunlight to check for sheen or rainbow effects that aren’t visible in shade. Rotating the stone slowly at different angles reveals hidden color layers. Pieces with a dull, chalky surface have weathered and generally aren’t worth keeping unless you plan to cut and polish them to expose fresh glass underneath.
For rainbow and fire obsidian specifically, smaller pieces often display better color than large chunks because the thin mineral layers that produce the effect are easier to see through less material. Many collectors bring a small spray bottle of water, since wetting the surface temporarily mimics a polished finish and makes it much easier to evaluate color and clarity in the field.