private Block[][] doCoalGen(Block[][] input){
		double height = 0;
		for(Block[] B : input){
			height = 0;
			for(Block b : B){
				height++;
				if(height > COAL_MAX_HEIGHT) continue;
				if(b == null) continue;
				if(Math.random() < COAL_GENERATION_COEFFICIENT * ((HEIGHT-height)/(double)HEIGHT)){
					int numBlocks = (int)(COAL_SPREAD_COEFFICIENT * Math.random());
					for(int i = 0; i < numBlocks; i++){
						if(b == null) continue;
						if(b.getType().equals("stone"))
							b.changeTo("coal");
						b = getRandomAdjacentBlock(b, input);
					}
				}
			}
		}
		return input;
	}