Southern Products & Silica 420021 50 lbs .8mm-1.2mm GP#2 Torpedo Quartzite Filter Sand. Our materials are hard quartzite, sub-angular sand and rounded gravel, free of clay, silt, iron, mica and other foreign matter. All filtering material is washed, screen-sized, washed and sized again according to current American Water Works Association B100 Standards for Filtering Materials and are NSF listed.