Answer:
Cuz its almost always man-made
Step-by-step explanation:
Believe it or not, glass is made from liquid sand. You can make glass by heating ordinary sand (which is mostly made of silicon dioxide) until it melts and turns into a liquid. You won't find that happening on your local beach: sand melts at an incredibly high temperature of 1700°C (3090°F) Although most people think of glass as a man-made material, it is found in many forms in the natural world. ... Scientists tell us that glass is a state of matter rather than a single material. Glass is created when molten material cools so rapidly that there is not enough time for a crystalline structure to form.
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