Abstract: The invention relates to a high density composite sheet based on discontinuous mineral fibers. The inventive sheet has a content of mineral fibers greater than 70 wt. % of the total weight of fibers and binder, and has a density between 400 and 1600 kg/m.sup.3. The sheet can be employed in particular as an architectural structural wall facing, as a component of a composite insulating panel, etc., and is formed by compressing at high pressure at least one non-woven layer of discontinuous mineral fibers provided with a polymerizable resin which is cured during compression.