the instant invention relates to the production of glass and glass - ceramic compositions containing a ferrimagnetic crystal phase throughout which respond thermally to fields generated by induction coils . magnetite is the preferred ferrimagnetic crystal phase because of its high permeability and low resistivity at room temperature as well as the relative low cost of iron when compared with other ferrimagnetic species . two general composition areas are of interest : na 2 o and / or k 2 o - feo - b 2 o 3 - sio 2 and li 2 o - al 2 o 3 - b 2 o 3 - sio 2 . where the coefficient of thermal expansion is sufficiently low to impart good thermal shock resistance , the compositions can be considered for top - of - stove cooking vessels .