Silicon is everywhere around us, it’s in the walls, in the windows, and in the ground under your feet. You wouldn’t recognise it in its pure form as a brittle metallic gray crystal, but silicon atoms (when joined with other elements) make up over a quarter of the mass of the Earth’s crust.
Sometimes pure silicon crystals are found, but only in special circumstances like in volcanoes. Usually silicon is found joined with oxygen in the form of quartz, or in other minerals and gemstones like obsidian, amethyst, opal, flint, granite, sandstone and many other kinds of rocks, clays and sands.
Silicon is a big component of glass – so the window nearest you has probably been made with the silicon dioxide found in sand. Sands and clays are also used in making cement, bricks and concrete, so pretty much every building around you is likely to be made from some kind of silicon.
Silicon Valley in California is named that because of how important silicon is to the technology they produce there. Pure silicon is used in circuits and microchips because of its properties as a semiconductor. This means that different amounts of electricity can flow through it under different conditions. Silicon chips are found in computerised devices such as phones, mp3 players and laptops.