Molten lava, cooled so quickly,  it didn’t have time to crystallise. Obsidian is a stone without boundaries, working very fast & with great power. Nothing can be hidden from Obsidian, with its truth enhancing & reflective qualities; this gemstone is merciless in exposing flaws. Can help in bringing negative emotions & unpleasant truths to the surface so that they can be dealt with once & for all. Strongly protective Obsidian forms a shield against negativity. Used by Shamans, Obsidian has the gift of prophecy, blocks psychic attack & absorbs negative energy from the environment. But it’s propensity for exposing the truth & bringing everything out into the open must not be dismissed. 
All our crystals come with a guide detailing some of their main properties, as detailed above.