Quartz is mainly used in silicon alloys and ceramic industries, though at times it is also used in the manufacture of glass. Quartzite is used in the manufacture of silica refractories and as a flux in iron and steel industry, silica sand is mostly used in the glass, sodium silicate industries and foundries.

The BIS has prescribed specifications for use in glass (IS: 28-1980) and foundry industries (IS: 1987 – 1974)

Glass Industry: Four grades of glass making sands are prescribed by the BIS for making glass.

Grades:

Special grade	For the manufacture of high-grade colorless glass, such as crystal glass, tableware and decorated ware.
Grade-I	For the manufacture of decolourised glassware, such as containware, lampware, etc.
Grade-II	For the manufacture of glassware, where a slight tint is permissible, and
Grade-III	For the manufacture of under-colonised some coloured glasses.
Size	The sizes of the grains constituting the material shall be with in the following limits:

Percentage by weight
1	Retained on 1mm sieve	Nil
2	Retained on 600 micron IS sieve (max.)	1
3	Passing through 600 micron IS sieve but retained in 300 micron IS sieve (max.)	50
4	Passing through 125 micron IS sieve (max.)	5

Chemical: The chemical compositions of the four grades of sand shall be as follows. This does not cover silica sand used for optical and other special glasses.

These requirements shall be as agreed to between the purchaser and the supplier.

Physical: The physical specifications of silica sand specifies that silica sand shall be fairly free from contamination like clay material, pebbles and other extraneous matter. The sand should not contain more than 4% moisture.

Specifications for by user Industries:
The natural silica sand is the most preferred material in a glass industry, but in some cases where the glass plants are located far away from silica deposits, crushed quartz is also used. For use in glass industry the silica sand must be uniform in chemical composition, size and shape of grains. Uniform grain size, promotes even melting in the glass tank. The sand should not be coarser than 20 or 30 mesh nor finer than 100 to 120 mesh. Very fine sand may be carried away by draft in the melting furnace. Both angular and rounded grains are used in the glass trade. As a general rule, the grains should be angular rather than rounded, because they melt more readily than the rounded ones.
Silica sand usually contains small amounts of iron oxide, alumina, chromium, magnesium oxide, calcium oxide, potassium oxide because it imparts coloration to the glass.