In 2017, a Dutch well known strahler discovered a spot with slag material from a former smelter (Hutte) in the Netherlands. The smelter was processing material from the area of Kelmis (B) and at its end-stage probably also processed material from Congo. I happend to be informed at an early stage and collected quite a few nice specimen of secondary ‘phases’. Since the minerals are developed on slag (left over of the smelter), they officially do not have the status of mineral although in nature they may occur as well. Another well known strahler from Köln assisted in identifying a few of them using EDX and Raman. But quite a few are still unidentified. Most of the fields of view are less than half a cm down to just 2-3 mm. The pictures of (Limonite after) Fougerite are exra interesting as the material is put on photo just after cracking (still black) and 24 hours later (orange). Who said the Netherlands are not interesting for mineral hunters?