Quartz is used for countertops in millions of homes around the world — the manmade stone is popular for its beauty and durability. But for workers who make, cut and install quartz counters, it can be deadly. The World reported from Turkey, Spain and Australia — three stops along the quartz countertop supply chain — to learn more about silicosis, an incurable and often fatal lung disease caused by inhaling dust laden with excessive amounts of a mineral called silica.