A briquette for use as a mineral charge in a cupola furnace for the production of mineral wool fibres is produced by combining: a) recycled waste mineral wool selected from i) waste mineral wool comprising uncured sugar containing binder, ii) waste mineral wool comprising cured binder, iii) waste mineral wool without binder and iv) combination thereof, b) cement, and c) additional sugar(s) to form a mouldable mixture and moulding and curing the mouldable mixture to form the briquette.