I'm sure many of you are aware that a method to mine slade by exploiting several glitches was discovered. It's a convoluted process explained on the wiki and in the
original thread. The basic idea is to drop a magma flow tile into the eerie glowing pit, using it to dig under the pit into a newly generated layer and into the slade from below. The new layer is generated based on the floor above it, so you may as well use raw adamantine.
What I've discovered isn't all that special. It's really just a (possibly world-dependent) simplification of the process summarized above, with maybe a new insight or two. The original discoverer may have missed it because it wasn't possible at his embark site, or maybe the world generation process has changed a bit in the past few months. I decided to create a new thread because original is old, long, and not entirely focused on the subject of slade mining. Plus, I've put together a rather detailed pictorial explanation. But enough introduction. Here's the simplified process:
1) Conditions, setup, and bonus candyFirst off, this method is only possible if you have slade floor on the lowest revealed layer of the embark square. I've entered hell in two fortresses recently, and both met this condition, so chances are good yours will, too. If the eerie pit extends even one layer deeper than the floor, you must use the older, more difficult process.
Now, on to the picture. The blue area is floored with raw adamantine (you'll need to enable it on the z-stone menu). This optional floor area will produce an extra layer of adamantine, but it will not produce slade. You can still get slade out of the unfloored areas. Don't bother flooring over the hills--you won't get anything out of them. On the right is an experimental demon-proofing apparatus. So far it's been successful, but that's a subject for another thread. The staircase was constructed on top of the eerie glowing pit, but anywhere on the bottom layer will do. The next step is to dig an
up stair directly below the down stair. An up/down staircase will prematurely reveal the next layer down.
2) Digging the first staircaseThis is what you'll see when you dig that staircase. If all you want is free candy, you can stop reading at the end of this section. The area underneath the floored area will be made of a material related to the floor you built. It gets a little weird if you don't use stone--you'll see a few examples in a moment. You can keep digging to the bottom of the map, and it'll all be the same stuff.
Don't go any deeper yet if you want slade!3) More floor, material scienceYou'll notice I've gone back up a level and expanded the floored area. The new floor is the area that will yield slade. The real purpose of step 2 was to generate a layer of slade to be mined. The candy was just a bonus.
You'll also notice I've included a few other materials in the floor this time, including metal bars, wood, soap, and glass. They produced some interesting results. The metal bars produced lumps of pure metal which can be melted or cut like gems. The glass produced rock. Just rock. That's literally the name of the material. It has a value of 3, like obsidian, and I assume it behaves like any normal stone. The wood (glumprong) and soap (rock nut) produced gems. More research needs to be done.
4)Generating candyHere you can see I dug down one more layer. You can dig as deep as you like at this point. A lot more adamantine has been generated, as well as the lumps of metal and gems.
5) Under the slade This is (still) two levels below the floor of Hell. I've prepared to dig upward into the slade. Because you can only mine unrevealed slade, you can't mine every tile. You can't really do better than this grid pattern, which nets you one piece of slade per four slade tiles.
6) FinishThis is the fully mined field of slade. The adamantine you see here was generated by the first floored area in step 1.
One last discovery of note: you can do this several times per map. Up to once per embark tile, if I'm correct. For example, if you have a 4x4 site, you can do this up to 16 times, once in each square of that 4x4 grid. Of course, not every one of those squares will have a good mining site, and you may reveal multiple embark tiles at once, so expect more like two or three chances.