Why does HTC U12's indestructible Corning Gorrila glass screen crack

[Android Central Question]

I bought HTC U12 because my previous HTC phones had screens that were truly unbreakable and unscratchable just like HTC had claimed. Those phones were accidentally dropped on stone walkway, cement pavement, and brick sidewalks many times. Nothing happened because the Corning Gorrila Glass was incredibly durable. iPhone glass broke easily. I asked why iPhone company did not used Corning Gorrila Glass.

Much to my surprise and disappointment, my HTC U12 glass screen cracked when it slipped from my hand and dropped 2 feet down to a table. I couldn't believe it. Why did it happen?

 

[belodion]

Glass is glass. You can call it something else if you like, but it’s still glass, and therefore breakable.