Obsidian forms from molten lava in the last stages of volcanic eruptions, the remaining silica minerals flow onto the surface and cool rapidly into glass before crystallization can occur. The colour of pure Obsidian is black, but there are other variations depending on inclusions of crystals where the lava cooled slower. The most common are mahogany, snowflake (white spots of crystobalite), rainbow and gold-sheen. Mahogany obsidian is a mixture of black and reddish brown. Lik
