Refractory building materials, not of metal, namely, refractory bricks; refractory ceramic masses, namely, refractory castable mixes not of metal and refractory concrete; refractory ceramic masses, namely, refractory casting, gunning, repair, and ramming masses not of metal; refractory ceramic building material being work pieces not of metal, namely, refractory ceramic blocks and refractory ceramic tiles; refractory ceramic shaped parts not of metal for building purposes, namely, refractory c...