Abstract: A graphite block for an induction furnace in the form of a right prism formed from a plurality of plates associated along adjacent end faces parallel to the axis of the prism. Each plate includes a longitudinal recess opening into its top face adjacent a first end and a longitudinal recess opening into its bottom face adjacent an opposite end. Each end face is provided with a flexible graphite joint. The association of plates results from a partial interfitting of a top face longitudinal recess of one plate with a bottom face longitudinal recess of a second plate, the recesses being adapted to leave a void of polygonal section between the plates. This void is occupied by a graphite key of similar section divided over its length into two parts meeting along an oblique surface.