The clay mineral composition of Triassic sediments in the Negev and Sinai depends upon the environment of deposition. Kaolinite predominates in continental and epicontinental sediments. The mineralogical composition of the marine clays resembles that of corresponding samples from North Africa and Europe, which comprise various mixtures and interstratifications of illite, montmorillonite, vermiculite and chlorite. Evaporitic sediments are poor in clay minerals and those present are largely detrital.
The results presented suggest that chlorite was formed diagenetically by prolonged percolation of seawater through pervious layers overlying impervious ones (hard beds).