silicification
... that silicification can produce opal ?
... that <b id="mwBqA"><a href="./Silicification" id="mwBqE" rel="mw:WikiLink" title="Silicification">silicification</a></b> can produce <a href="./Opal" id="mwBqI" rel="mw:WikiLink" title="Opal">opal</a> <i id="mwBqM">(example pictured)</i><span about="#mwt82" data-mw='{"parts":[{"template":{"target":{"wt":"-?","href":"./Template:-%3F"},"params":{},"i":0}}]}' id="mwBqQ" style="padding-left:0.15em;" typeof="mw:Transclusion"><span typeof="mw:Entity">?</span></span>