A whole mountain of volcanic glass in the Oregon high desert, and one of the best obsidian collecting sites in the world. It is not just black: there is rainbow sheen, gold and silver sheen, mahogany, snowflake and the prized fire obsidian, all yours to collect on this BLM ground with no fee and no permit. There is a ceiling on it, though, and it is worth knowing before you fill the boot: the BLM sets a daily and a yearly weight limit for personal collecting, and it is for your own use or enjoyment only, never for sale or barter. The figures move, so check the current ones with the Prineville District before you load up. Knappers come from everywhere for it. PUBLIC (BLM, weight-limited), between Bend and Burns; high, remote and dry, so come prepared and take a real spare.
Obsidian (rainbow, mahogany, fire)
Other places on the map within a couple of hours.