“[W]e can interpret... two elements... of the industrial activities. First, we may suppose that there had been exhaustion in the Sinai mines. Some minerals are used to make artificial stones, and we have texts... that show... the Sinai mines were very heavily exploited, and afterwards, no longer. Or the manufacture or lime-ash generated an ecological disaster. This is the lime... in the reaction... [with] the {{w|Natron}} ({{w|sodium carbonate}}) [in water] to... produce the caustic soda that will start the {{w|geopolymer}}ic reaction.”