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What is window glass made of?
Ordinary window glass is not pure silica. It is usually a soda-lime-silica glass designed to melt, form and survive everyday use more easily.
Silicon dioxide provides the main network. Sodium-containing ingredients lower the temperature needed for processing, while calcium-containing ingredients help make the finished glass more chemically durable.
Glass is an amorphous solid: its atoms do not form the long-range repeating crystal structure found in materials such as quartz. That does not mean glass is a liquid flowing slowly at room temperature.
Coatings can add other functions. Very thin metal or metal-oxide layers can reflect infrared radiation, reduce heat transfer or modify the colour and solar performance of architectural glass.
Why this object uses several materials
Most manufactured objects solve several problems at once: strength, electrical conduction, thermal behaviour, corrosion resistance, weight, appearance and cost. One pure material rarely satisfies all of them.
That is why a useful way to read an object is part by part. Each component reveals a different compromise between chemistry, physics and engineering.
What changes in practice
Real examples often add one more layer: geometry, impurities, coatings, humidity, flow or manufacturing history can alter what you observe even when the main mechanism is unchanged.
That is why two objects made from broadly similar materials can behave differently. The useful question is not only “what is it made of?” but also “how is it built, under what conditions, and for which function?”