Michelnau Quarry

Among other things, the Frau Rauscher Fountain ("Fraa Rauscher") in Frankfurt's Sachsenhausen district was built from the Michelnauer tuff.
Here is an excerpt from the Hessenschau from October 10th, 1961 about the basalt quarry in Michelnau: ardmediathek.de/video/hr-retro-oder-hessenschau/der-basaltsteinbruch-im-michelnau/hr-fernsehen/Y3JpZDovL2hyLW9ubGluZS8xNDA5OTc

Red tuff is or was only mined in a few places worldwide. We highly recommend: de.wikipedia.org/wiki/Michelnauer_Tuff... and how to get a guided tour; is here: steinbruch-michelnau.de

Volcanic tuff was mined in Michelnau more than 100 years ago. Tuff consists of volcanic slag that was compressed into stone over a period of 15 - 17 million years. The work was purely mechanical and manual; the tools are still available and can be inspected. The Friends of the Michelnauer Steinbruch e.V. offer guided tours. Definitely recommendable!