Abstract: Flakes of glass, basalt or other frangible material are formed by feeding a stream of the molten material in a downwards direction into a rotating cup (5) which has its open mouth facing upwardly with its rim disposed at a horizontal level between a pair of spaced apart parallel plates (9 and 11) which are mounted within a vacuum chamber (13) in such manner that, as air is drawn from outside the chamber (13) between the plates (9 and 11) the molten material is drawn radially outwardly without touching the plates and is cooled with the continuing outward movement causing the material to be broken into flakes.