Hierarchy classification:

1. top of the aat hierarchies
2. Materials Facet
3. Materials (hierarchy name)
4. materials (substances)
5. [materials by composition]
6. inorganic material

Additional parents:

1. top of the aat hierarchies
2. Materials Facet
3. Materials
4. materials
5. materials by form
6. materials by chemical form
7. elements

Anotations

Scope note:

Semi-metallic element, having symbol Si and atomic number 14, in amorphous and crystalline forms, occurring in a combined state in minerals and rocks and constituting more than one fourth of the earth's crust. The chemical industry uses the term "silicon metal" and "silicon" interchangeably, and anything but pure silicon is generally referred to in this context as "semiconductor-grade silicon."