Perhaps the most characteristic lithology in the Monterey Formation is porcelanite, a hard siliceous sedimentary rock with the matte texture and dull luster of unglazed porcelain (hence the name). It is formed by the diagenetic alteration of diatomaceous sediments that are a mixture of silica and mud. It is not as purely siliceous as chert. Photo © Rick Behl (1997).
Or click 
here to return to the
Department of Geological
Sciences home page
