Using glass as an example of fragility is actually really unfair to glass. Glass is much harder than most rocks are, it’s just the thin shapes we form it into that makes it fragile.

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Hardness is not the same as strength. Hardness refers only to how hard it is to scratch it, not how easy it is to break. Diamonds are the hardest things we know, but they are easily shattered with a hammer. Also, glass is right in the middle of the Mohs hardness scale, meaning it is not harder than *most* minerals, just harder than about half of them. And finally, an inch think pane of glass would still break easier than most rocks in a similar sheet.


Time for science! The other comments have covered the difference between strength and hardness but here’s something you probably didn’t know. If you look at the chemical structure of glass it should be incredibly strong with a tensile strength of around 17 gigapascals(2,500,000psi) but when measured it’s only about 7 megapascals(1000psi). So we measure glass at 10,000 times less than it’s expected strength. This is due to imperfections in the good like micro bubbles and scratches. If we could form a perfect piece of glass without those imperfections it would be 10,000 times stronger.


Try breaking a tough pebble with your shoe.


Yeah for sure. I mean have you ever actually tried to break a glass bottle? You have to be super intentional and aggressive to manage to break it.


Sorry, Mr. Glass, you have to change your name