In the southern part of the crystalline Spessart, diorite is extracted in the only quarry still in operation and, by today's standards, relatively small. Within the diorite, there are dark inclusions of biotite-plagioclase slate, quartz and pegmatite veins and, more rarely, younger fissures with epidote and actinolite with remarkable minerals.
The quarry was started by Erwin Stahl in 1958. It is operated on three levels by the Erwin Stahl Hartsteinwerk company in Dörrmorsbach. It is mainly mined in large pieces and the following products are obtained from it: rubble stones for bank reinforcements (more than 75%, the only quarry for waterworks stones), coarse gravel and (to a lesser extent) wall stones and "erratics" for garden design and as memorial stones.