# What temperature is really required to make fused quartz? [closed]

Glass transition temperature of fused quartz is 1200 °C. Does this mean it can be made by heating sand to 1200 °C, or does the melting point of $$\ce{SiO2}$$ has to be reached (~1700 °C) for that to happen?

• See here for glass transition temperatures. Jul 19 '20 at 19:32
• Most "glass" is not pure quartz (which is silicon dioxide). Usually many other ingredients are added to lower the melting temperature and/or to make the properties different. Jul 19 '20 at 20:48
• Fused silica is not the same as fused quartz. Fused silica fluorescence cuvettes are an example. Even high purity natural quartz crystals have significant levels of impurities, e.g., aluminum.
– Ed V
Jul 20 '20 at 1:35

Glass is not necessarily made of pure silica $$\ce{SiO2}.$$ Ordinary glass is a mixture of at least $$50\,\%$$ $$\ce{SiO2},$$ plus smaller proportions of $$\ce{CaO},$$ $$\ce{Na2O},$$ $$\ce{K2O},$$ and $$\ce{Al2O3},$$ with impurities like $$\ce{Fe2O3}.$$ Pyrex has also some $$\ce{B2O3}.$$