Obsidian is a volcanic glass formed when felsic lava cools rapidly, minimizing crystal growth. Historically it has been used for weapons, tools and even a surgical edge. When processed correctly, obsidian will provide a long lasting very sharp edge.
You can find A LOT of obsidian in Newberry Caldera about 20mi/32km south of Bend in central Oregon. It is similar to Mt. Mazama being a caldera. While the caldera of Mt. Mazama houses Crater Lake, the Newberry volcano caldera houses East Lake and Paulina Lake.
How large is Mt. Newberry? The caldera is 4 by 5 mi/6.5x8km in diameter. There are more than 400 vents, the most of any volcano in the contiguous U.S. The volcano itself has an area of 1,200 sq mi/3,100 sq km being 75x27mi/120x43km in size. This one volcano is about the same size as the state of Rhode Island.
Heading south of Bend on Hwy-97, just follow the signs to the Newberry National Volcanic Monument. You’ll see the signs for the “Big Obsidian Flow”. The lava flow is a short flat walk from your vehicle. A trail up the flow is there, for those that want to see more… There is also a network of cinder cones, caves, a lava cast forest, and so much more in the area, if you are adventuresome.
Location via Google Maps