The 6,000-year-old Mehrgarh amulet isn’t much to look at—a somewhat misshapen copper wheel just under an inch in diameter, with six spokes projecting from a central hub. But the historical importance ...

Colloidal silica is a mainstay for everyday applications such as papermaking, polishing the silicon wafers used to make computer microchips, making nonslip and abrasion-resistant coatings, and soaking ...

Silicon oxides such as SiO 2 are the most abundant component of the earth’s crust. They can be found in nature in crystalline form and are industrially manufactured in many forms, including colloidal ...