Part of a 60kg gift from a strahler from the Stolberg area was some limited material from Untermaubach. I have never been there, so the only thing I can do is repeat the text of Midat.org: Triassic greywacke-quartz conglomerates including lead and minor zinc and copper ores, covered by a layer of sandstone. The deposit was worked from an open cut for several centuries and finally abandoned in 1969. Today, after some decades of use for dumping rubbish, the site is completely backfilled.
Located 2 km NNW of Untermaubach and about 7 km SW of Düren.