The present invention relates to a heat-insulating material, in particular in the form of a solid foam, based on mineral particles of submicron porosity, this material incorporating two different ranges of porosities, advantageously including a first range consisting of (macro)pores with diameters of between 10 microns and 3 mm, and a second range consisting of submicron pores with diameters greater than 4 nm and less than 1 μm, the pore volume of said submicron pores being at least 0.5 cm3/g and the mass per unit volume of said insulating material being less than 300 kg/m3.
