Silicon is neither metal nor non-metal; it's a metalloid, an element that falls somewhere between the two. The category of metalloid is something of a gray area, with no firm definition of what fits the bill, but metalloids generally have properties of both metals and non-metals. They look metallic, but conduct electricity only intermediately well. Silicon is a semiconductor, meaning that it does conduct electricity. Unlike a typical metal, however, silicon gets better at conducting electricity as the temperature increases (metals get worse at conductivity at higher temperatures).
Silicon was first isolated in 1824 by Swedish chemist Jöns Jacob Berzelius, who also discovered cerium, selenium and thorium, according to the Chemical Heritage Foundation. Berzelius heated silica with potassium to purify silicon, according to the Thomas Jefferson National Accelerator Facility, but today the refinement process heats carbon with silica in the form of sand to isolate the element.