SiO2 and B2O3 glasses have extreme properties. If more broadly useful glasses are to be had, pure oxide glasses need to be modified by adding other elements, called, naturally, Network Modifiers. The strong Si-O bonds, which account for the exceptional properties of SiO2 glass, are perturbed by Network Modifiers. It is exceptional to use B2O3 as a lone glassformer. Usually, B2O3 and SiO2 are combined to form what is known as Borosilicate glasses.
Borosilicates are a diverse and widely used class of glasses.
We will also take them up further along. So keep them in mind. For now though we will focus on the effects network modifiers have on SiO2 based glasses. Since ancient times just about every element on the planet, and some which weren't, have been added to silica host glasses. In modern Studio setting, the range of compositions used has practical limits.