The Tarcoola Formation contains partially silicified specimens which are dolomitic and occur as clasts in a conglomerate, and totally silicified in situ forms. Although short sections of the latter stromatolites are columnar, none shows sufficient characters to allow detailed comparison with previously described taxa. The stromatolites are of no biostratigraphic significance. Stromatolite like concretions in silicified carbonates are interpreted as having been formed by diagenetic infiltration of carbonate by silica, with diffusion banding and subsequent leaching of carbonate, followed by crystallization of quartz in resulting open spaces.