Missing stuff:
The Helper class should be in a different package, the value of Ores generated per ore spawn should probably be configurable. Additionally, the default config could be adapted to more realistic values.
What does this code do?
it uses weights for determining what ores to spawn
it spawns many "lesser" ores to keep the quarry useful when adding stuff with high weight. This is archived by giving each ore a value (=1/weight) and adding more ores until a set total value (the value of the rarest ore, in the current implementation, should probably configurable) is exceeded.
Missing stuff: The Helper class should be in a different package, the value of Ores generated per ore spawn should probably be configurable. Additionally, the default config could be adapted to more realistic values.
What does this code do?