This resource is mined in the Scottish village of Lochaline, which was visited by Ed Conway in the first of six parts of a 2023 book. Chinese vessels have attempted to covertly collect this (15[1])resource from Taiwan’s Matsu Islands. (15[1])India has violent “mafias” that illegally export (15[1])this resource, whose mining has endangered (15[1])gharials and Lake Poyang’s freshwater porpoises. Environmentalists have decried Indonesia’s massive exports to this resource’s largest (-5[1])importer, (*) Singapore. New Jersey has spent billions on “nourishment” projects that have replenished this (-5[1])resource after a 2012 natural disaster. A U.S. admiral claimed that China was making a “Great Wall” of this resource in the South China Sea as part of its reclamation process. This substance is dredged to manufacture concrete. For 10 points, name this silica-rich substance collected from beaches. ■END■ (10[2])