- a nonmetallic element, having amorphous and crystalline forms, occurring in a combined state in minerals and rocks and constituting more than one fourth of the earth's crust: used in steelmaking, alloys, etc. Symbol: Si; atomic weight: 28.086; atomic number: 14; specific gravity: 2.4 at 20°C.
- a brittle metalloid element that exists in two allotropic forms; occurs principally in sand, quartz, granite, feldspar, and clay. It is usually a grey crystalline solid but is also found as a brown amorphous powder. It is used in transistors, rectifiers, solar cells, and alloys. Its compounds are widely used in glass manufacture, the building industry, and in the form of silicones. Symbol: Si; atomic no: 14; atomic wt: 28.0855; valency: 4; relative density: 2.33; melting pt: 1414°C; boiling pt: 3267°C
- denoting an area of a country that contains a density of high-technology industry
