Borosilicate glass is a low soda glass consisting primarily of the following, 70% silica, 10% boric oxide, 8% sodium oxide, 8% potassium oxide and 1% calcium oxide.
Although somewhat more difficult to make than traditional glass it is economical to produce because of its superior durability. Chemical & heat resistance properties are of excellent use in chemical laboratory, military uses and a variety of others. Borosilicate glass has a very low thermal expansion coefficient making it a popular material for flat TFT screens and other critical display equipment.
Optically, borosilicate glasses are crown glasses with low dispersion and relatively low refractive indices (1.51 – 1.54 across the visible range).