The value of obsidian, a natural volcanic glass, is difficult to determine due to the variety in its deposits and the fact that it is not traded as a commodity like gold or oil. Common black obsidian is often priced according to its weight and quality, with 1 gram of obsidian worth around $0.005. Rarer forms of obsidian, such as fire obsidian, would likely need to be priced by a professional appraiser. The price of obsidian largely depends on the purity, size, or color of the ore, and it can also depend on the geographical location of the obsidian market.