Light micrograph of a thin section of silicon (symbol Si). Silicon is a non-metallic element with atomic number 14 and atomic weight 78.09. It is most familiar as a major component of microelectronic devices, known popularly as 'silicon chips'. Silicon is also used in glass manufacture and as a strengthening alloy in steel. In the dioxide form, SiO2, it forms the commonest mineral on Earth, seen as quartz and as a variety of semi-precious minerals such as agate, onyx and jasper. Magnification: x62 at 6x4.5cm size.