The synergistic composition consists of a mixture of a source of pure silica such as silicon dioxide, a source of carbon such as activated charcoal, .beta.-silicon carbide and a source of iron such as ferric nitrate. The cost effective synergistic composition is useful for the preparation of improved silicon carbide powder containing at least 90% SiC preferably rich in the .beta.-phase. Silicon carbide powder finds wide usage in the manufacture of products suitable for refractory and engineering applications.