Sulphur ore generation

There's a lot of tweaking I'd like to do, but I think this is a pretty good result for a first try.

I tried using WorldGenMinable to generate the clusters of ore, but it had a habit of spawning 6-7 blocks away from the lava.

I'm not quite game enough to put in the configuration options myself yet as I'm still trying to get a feel for your coding style before I try doing infrastructural. I have however declared the configurable settings as variables at the top of the method.
I've generally used LinkedLists for fast traversal when I have no idea how big a collection is likely to grow. In this case however, creating an Array List of size (maxClusters) would be appropriate, and like your other suggestion, we can clear it every time.

I'll admit to being a bit weirded out by that though as I'm rather used to designing classes with concurrency in mind. Designing classes that are inherently thread-unsafe feels very strange to me. If I had c#'s parallel library, I'd totally multithread this thing >:D