Before being able to craft these Power Cells, it's necessary to unlock the crafting-recipe by crafting or taking a Stone Mining Cell.
To craft one Obsidian Mining Cell, you'll need (as of R43 in May 2017):
- 4 Obsidian (bars) made in a Forge from Obsidian Ore (found in Nodes on the Fossil layer or in the Mountains, later on also in Iron Treasure Chests and Diamond Treasure Chests)
- 2 Stone Slabs made of Stone, Limestone or Bedrock in a Processor
- 10 (blocks of) Bedrock mined from the Fossil layer, which requires at least a Stone Mining Cell or better
- 8 (blocks of) Magnetite mined from the Fossil layer, which requires at least a Stone Mining Cell, or can be looted/pet-harvested from Rocksters, Night Rocksters or Warmworms
- 4 Mushrooms; either Red Mushroom, Brown Mushroom or rare Glowing Mushroom can be used (click on the blue arrows to choose)
Taking or crafting an Obsidian Mining Cell currently is one of the requirements to unlock the crafting recipes for Iron Mining Cells, for the very useful Advanced Extractors (they can extract twice as much Ore from any Node as the Basic Extractor), Plows (since R22), Pressure Plates (since R34), Salt, Adobe Walls, Blue Concrete, Red Concrete, Yellow Concrete and Flower Pots.
As for liquids; you can pull common blue Water with Obsidian Mining Cells (and Molasses even without needing any Power Cells), but not Tar, Bog Water, liquid Lava, Mineral Water nor Corrupted Water - all of the latter ones will need stronger Power Cells.
The Obsidian Mining Cell in general has a better durability (lasts longer) than the Stone Mining Cell. As for R32 (June 2016), it is believed that this Power Cell can mine 350 blocks from the Stalactite layer (T3) such as Stalactite, Siltstone and the like, or 700 blocks of the Fossil layer (T2) like Bedrock or Limestone and also 700 blocks of the hardness of Stone or Canyonstone (T1).
The Obsidian Mining Cell can extract infinite amounts of blocks that wouldn't even need any Power Cells to be foraged, like Dirt, Grass, non-corrupted Wood, Logs, plants, Red Mushrooms, Brown Mushrooms and the like (T0)