Gary,
maybe anybody out there has information on quarries in that area, I don't know any. (Yes, I know one or two, but these are not really close and for cement and gravel production).
Also - you'll probably realize that he could have lived and worked there without a quarry? There were many (are a few) stone cutters, I would guess that only a minority would have(had) a quarry near by. The others were/are working with stone that's getting delivered as huge blocks to their workshops - that's at least what I would think.
My CD-phone-directory has still 2
Schlager entries for Altlengbach. I think writing 2 letters might be worth a try (best to write them in
English *and*
German).
Tilman