Obsidian – Official Minecraft Wiki
Obsidian also occurs naturally where underwater springs flow onto lava, often at layer 10 or lower. Obsidian also generates in woodland mansions in a tree shape with a diamond block in the middle of it. Chests . Obsidian can be found in % of nether fortress chests in stacks of 2–4, and in % of village blacksmith chests in stacks of 3–7.