This old Dutch coalmine dump near Kerkrade is partly burning. Like with vulcanic fumaroles, cristals are formed from the fumes, mostly at places where the temperature drops (e.g. directly on the surface, where temperatures may still be over 200 and even 340 degrees Celcius. The resulting red material is processed as gravel. Visiting the site is most rewarding after a long dry period, but is prohibited without permission. Next to the fumarole material there are pieces of quartz with nice and rare minerals and occasionally great fossiles. A piece with Bismite (confirmed with EDX and Raman) was a very special find for the Netherlands (not mentioned in any literature before).